Medical Calculators
Browse all available clinical calculators.
A–a Oxygen Gradient
Calculates the alveolar-arterial oxygen gradient to assess gas exchange abnormalities.
ABCD2 Score for TIA
The ABCD2 score stratifies the short-term risk of stroke after a transient ischemic attack (TIA) using Age, Blood pressure, Clinical features, Duration of symptoms, and Diabetes. The total ranges 0–7 and estimates the 2-day risk of subsequent stroke.
Adjusted Body Weight
Calculates Adjusted Body Weight using the Devine Ideal Body Weight formula.
Adrenal Steroid Converter
Converts between equivalent glucocorticoid and mineralocorticoid doses of commonly used adrenal steroids.
ALBI Score (Albumin-Bilirubin)
Objective prognostic assessment of liver function using serum albumin and bilirubin. Primarily validated in hepatocellular carcinoma (HCC) for stratifying prognosis and guiding treatment decisions.
Albumin to Globulin Ratio (A/G)
Calculates the albumin to globulin ratio from serum albumin and total protein (A/G ratio = albumin / (total protein − albumin)). The ratio is used as a screening aid in the evaluation of liver disease, nephrotic syndrome, and monoclonal gammopathies, alongside the absolute albumin and globulin values.
Albumin-to-Creatinine Ratio
Calculates urine albumin-to-creatinine ratio (ACR) for CKD screening and staging.
Alvarado Score (Appendicitis)
Risk-stratifies patients with suspected acute appendicitis using the Alvarado (MANTRELS) scoring system. Assists in clinical decision-making regarding imaging, observation, and surgical consultation.
Anion Gap
Calculates the serum anion gap using sodium, chloride, and bicarbonate. The anion gap helps differentiate high anion gap metabolic acidosis (HAGMA) from normal anion gap metabolic acidosis (NAGMA).
Anion Gap Delta Ratio (ΔAG/ΔHCO3)
Calculates the anion gap delta ratio to evaluate the acid-base response in a high anion gap metabolic acidosis: ΔAG/ΔHCO3 = (measured anion gap − 12) / (24 − measured HCO3). It helps identify mixed acid-base disorders such as a concurrent non-anion gap acidosis or metabolic alkalosis.
Apgar Score (Newborn)
Scores newborn condition at 1 and 5 minutes using the five Apgar signs (Appearance, Pulse, Grimace, Activity, Respiration), each scored 0–2 for a total of 0–10 (Apgar 1953). Higher scores indicate better transition to extrauterine life.
ApoB / ApoA1 Ratio (ApoB:ApoA1)
Calculates the apolipoprotein B to apolipoprotein A1 ratio (ApoB:ApoA1), an index of the balance between atherogenic (ApoB) and anti-atherogenic (ApoA1) lipoproteins used in cardiovascular risk assessment.
APRI Score
AST to Platelet Ratio Index (APRI) for estimating liver fibrosis and cirrhosis.
ASCVD Risk (Pooled Cohort Equations)
10-year risk of atherosclerotic cardiovascular disease (first nonfatal myocardial infarction, coronary heart disease death, or fatal/nonfatal stroke) using the 2013 ACC/AHA Pooled Cohort Equations, the basis of the 2018 ACC/AHA cholesterol guideline statin decisions.
Atherogenic Index of Plasma (AIP)
Calculates the atherogenic index of plasma (AIP), a logarithmically transformed ratio of triglycerides to HDL cholesterol that reflects the balance of atherogenic and protective lipoproteins.
Barthel Index
The Barthel Index (Mahoney & Barthel 1965) measures functional independence in activities of daily living across ten domains (feeding, bathing, grooming, dressing, bowels, bladder, toilet use, transfers, mobility, stairs), yielding a total of 0–100. Higher scores reflect greater independence: 0–20 total dependence, 21–60 severe, 61–90 moderate, 91–99 slight dependence, and 100 independence. It is widely used in stroke, rehabilitation, and geriatric care, including the Shah 1989 modification for ordinal scoring.
Basal Metabolic Rate
Estimates basal metabolic rate using the Mifflin-St Jeor equation.
Biophysical Profile (BPP)
Scores fetal well-being (Manning 1980) from five components — fetal breathing, gross body movement, fetal tone, amniotic fluid volume, and (in the full BPP) a non-stress test — each scored 0 or 2 for a total of 0–10. Higher scores indicate reassuring fetal status; lower scores identify fetuses at risk who warrant delivery planning.
Bishop Score
Scores cervical readiness for induction of labor (Bishop 1964). Five components (dilatation, effacement, station, consistency, position) are each scored 0–3 (or 0–2) and summed to a total of 0–13; higher scores predict a higher likelihood of successful induction and vaginal delivery.
BODE Index (COPD Prognosis)
Multidimensional prognostic index for COPD based on Body mass index, airflow Obstruction, Dyspnea, and Exercise capacity. Predicts mortality and guides clinical decision-making including transplant evaluation.
Body Mass Index (BMI)
Calculates Body Mass Index.
Body Surface Area (BSA)
Calculates Body Surface Area (Mosteller formula).
BUN/Creatinine Ratio
Calculates the Blood Urea Nitrogen to Creatinine ratio to help differentiate causes of kidney dysfunction.
Calcium-Phosphate Product
Calculates the calcium-phosphate product used in renal risk assessment for vascular calcification.
Calculated LDL (Friedewald Equation)
Estimates low-density lipoprotein cholesterol (LDL-C) from a standard fasting lipid panel using the Friedewald equation: LDL = total cholesterol − HDL − (triglycerides / 5). Used for cardiovascular risk assessment and lipid-lowering treatment targets. Not valid when triglycerides are ≥ 400 mg/dL.
Calorie Requirement
Estimates daily calorie requirement from basal metabolic rate and activity level.
CHA₂DS₂-VASc Score
CHA₂DS₂-VASc score for stroke risk stratification in patients with non-valvular atrial fibrillation, guiding anticoagulation decisions (score 0–9).
Charlson Comorbidity Index (CCI)
The Charlson Comorbidity Index (Charlson 1987) predicts one-year and ten-year mortality from a weighted count of 19 comorbidities (weights 1, 2, 3, and 6) plus an age adjustment (per decade over 40, 1994). Higher scores indicate greater comorbidity burden and lower estimated ten-year survival, with wide application as a case-mix adjustment in outcomes research and clinical prognostication.
Child-Pugh Score
Estimates severity and prognosis of chronic liver disease and cirrhosis.
CKD-EPI 2021 eGFR Equation
Estimates glomerular filtration rate (eGFR) using the 2021 CKD-EPI creatinine equation.
Cockcroft-Gault Equation
Estimates creatinine clearance (CrCl) for medication dosing using the Cockcroft-Gault equation.
Corrected Anion Gap
Calculates the albumin-corrected anion gap. In hypoalbuminemia, the measured anion gap is falsely low, potentially masking a high anion gap metabolic acidosis. This correction adjusts for the albumin contribution.
Corrected Calcium
Calculates corrected total serum calcium adjusted for hypoalbuminemia. In hypoalbuminemia, measured total calcium is falsely low because less calcium is protein-bound; this correction estimates the physiologically active total calcium.
Corrected Magnesium (Albumin-Adjusted)
Adjusts measured serum magnesium for hypoalbuminemia. When serum albumin is low, measured total magnesium is falsely reduced because less magnesium is bound to proteins. This correction estimates the physiologically relevant magnesium level.
Corrected QT
Corrects the QT interval for heart rate using the Bazett formula.
Corrected Sodium
Corrects serum sodium for hyperglycemia using the conventional correction factor. Hyperglycemia draws water into the extracellular space, diluting sodium; this correction estimates what sodium would be at a normal glucose level.
CRB-65
CRB-65 severity score for community-acquired pneumonia risk stratification, usable without laboratory testing (Confusion, Respiratory rate, Blood pressure, age 65+).
Creatinine Clearance from 24-Hour Urine (CrCl)
Calculates creatinine clearance from a 24-hour urine collection using urine creatinine, serum creatinine, and 24-hour urine volume. It is the classic timed-collection estimate of GFR.
CURB-65 Score
CURB-65 severity score for community-acquired pneumonia.
DAPT Score
Dual Antiplatelet Therapy (DAPT) score for decision-making about the duration of dual antiplatelet therapy after coronary stenting, balancing ischemic benefit against bleeding risk (score −2 to +10).
ECOG Performance Status
The ECOG (Eastern Cooperative Oncology Group) performance status (Oken 1982) grades a patient's functional capability on a single scale from 0 (fully active) to 5 (dead). It is a cornerstone of oncology decision-making — used to select patients for chemotherapy and clinical trials, dose-intensity treatments, and estimate prognosis — and is widely applied in geriatrics and general medicine for patients with chronic or serious illness.
EDD
Estimates the expected date of delivery from the last menstrual period.
Edinburgh Postnatal Depression Scale (EPDS)
Screens for postpartum (and antenatal) depression using the 10-item Edinburgh Postnatal Depression Scale (Cox 1987). Each item is scored 0–3 for a total of 0–30. A total ≥ 10 (or ≥ 13 in some settings) is screen-positive, and any positive response on item 10 (self-harm) requires immediate evaluation.
Electrolyte-Free Water Clearance (EFWC)
Calculates urinary electrolyte-free water clearance (EFWC) from urine flow and urinary/plasma sodium and potassium. It is used to distinguish renal from extrarenal water losses and to guide fluid therapy in dysnatremia.
Epworth Sleepiness Scale
The Epworth Sleepiness Scale (Johns 1991) measures daytime sleepiness by asking how likely the patient is to doze in eight common situations, each scored 0–3 (total 0–24). Higher scores indicate greater sleep propensity: 0–10 normal, 11–14 mild, 15–17 moderate, and ≥ 18 severe excessive daytime sleepiness.
Essen Stroke Risk Score
The Essen Stroke Risk Score (ESRS) estimates the long-term risk of recurrent stroke in patients with a history of ischemic stroke or TIA. Points are awarded for age, hypertension, diabetes, prior myocardial infarction, other cardiovascular disease, peripheral arterial disease, smoking, and prior ischemic events; the total ranges 0–9.
Estimated Average Glucose (eAG)
Estimates mean plasma glucose from HbA1c using the ADAG formula validated by the American Diabetes Association.
Estimated Blood Loss (Obstetric)
Estimates intraoperative blood loss in obstetrics by two methods: gravimetric (weighed sponges/drapes, 1 g ≈ 1 mL blood) and hematocrit-based (EBL = estimated blood volume × (pre-Hct − post-Hct)/pre-Hct, using a pregnancy blood volume of approximately 85 mL/kg). Postpartum hemorrhage is defined as cumulative blood loss ≥ 1000 mL within 24 hours.
FIB-4 Index
Non-invasive score used to estimate liver fibrosis in chronic liver disease.
Fluid Requirement
Estimates maintenance fluid requirement based on body weight.
FOUR Score
The FOUR (Full Outline of Unresponsiveness) score assesses coma depth using four components — Eye response, Motor response, Brainstem reflexes, and Respiration — each scored 0–4 for a total of 0–16. Lower scores indicate deeper coma and higher in-hospital mortality.
Fractional Excretion of Calcium (FECa / Calcium–Creatinine Clearance Ratio)
Calculates the fractional excretion of calcium (calcium–creatinine clearance ratio, CCCR) to help distinguish familial hypocalciuric hypercalcemia (FHH) from primary hyperparathyroidism in patients with hypercalcemia and non-suppressed PTH.
Fractional Excretion of Phosphate (FEP)
Calculates the fractional excretion of phosphate (FEP) to localize the cause of hypophosphatemia: a high FEP indicates renal phosphate wasting, whereas a low FEP suggests redistribution or extrarenal loss.
Fractional Excretion of Sodium (FENa)
Calculates the fractional excretion of sodium to distinguish prerenal azotemia from acute tubular necrosis.
Fractional Excretion of Urea (FEUrea)
Calculates the fractional excretion of urea for renal evaluation, particularly useful when diuretics are present.
Fractional Excretion of Uric Acid (FEUA)
Calculates the fractional excretion of uric acid (FEUA) to help distinguish prerenal azotemia from intrinsic renal injury in acute kidney injury, and to assess uric acid handling (e.g., SIADH, tumor lysis, Fanconi syndrome).
Free Thyroxine Index (FTI / T7)
Calculates the free thyroxine index (FTI or T7) from total T4 and the T3 resin uptake, an indirect estimate of free thyroid hormone used when direct free T4 assays are unavailable or when binding-protein status is in question.
Free Water Clearance (CH₂O)
Calculates renal free water clearance (CH₂O) from urine flow, urine osmolality, and plasma osmolality to characterize renal water handling in polyuria, hyponatremia, and hypernatremia.
Free Water Deficit
Estimates free water deficit in hypernatremia. Helps quantify the amount of free water needed to restore normal sodium levels.
Generalized Anxiety Disorder 7-Item Scale (GAD-7)
The GAD-7 (Spitzer 2006) screens for and grades the severity of generalized anxiety symptoms over the prior two weeks. Seven items are each scored 0–3 (total 0–21), with a cut-point of 10 maximizing sensitivity (~89%) and specificity (~82%) for generalized anxiety disorder; scores fall into minimal, mild, moderate, and severe bands.
Gestational Age
Estimates gestational age from weeks and days.
Gestational Weight Gain (IOM 2009)
Provides the Institute of Medicine (IOM/NRC 2009) recommended total gestational weight gain and second/third-trimester rate based on pre-pregnancy body mass index (BMI). Categories: underweight (< 18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥ 30).
Glasgow Coma Scale
Glasgow Coma Scale.
Glasgow-Blatchford Score
Predicts the need for intervention or mortality in patients with upper gastrointestinal bleeding.
Gorelick Dehydration Scale
Predicts clinically important dehydration (≥ 5% body weight) in children with gastroenteritis using the validated 4-item Gorelick scale: capillary refill > 2 seconds, dry mucous membranes, absent tears, and ill/toxic appearance. Three or more of four findings predicts ≥ 5% dehydration.
GRACE Risk Score (In-Hospital)
Global Registry of Acute Coronary Events (GRACE) in-hospital risk score for acute coronary syndromes, estimating in-hospital mortality from age, heart rate, systolic blood pressure, creatinine, Killip class, cardiac arrest, ST-segment deviation, and cardiac enzymes.
H2FPEF Score
H2FPEF score for estimating the probability of heart failure with preserved ejection fraction (HFpEF) in patients with unexplained dyspnea (score 0–9).
Hadlock Estimated Fetal Weight
Estimates fetal weight from four standard ultrasound biometric measurements (BPD, head circumference, abdominal circumference, and femur length) using the Hadlock four-parameter formula (1985). Output is the estimated fetal weight in grams, with the characteristic ±1 SD error of approximately 7.5%.
Harris-Benedict
Estimates basal metabolic rate using the Harris-Benedict equation.
HAS-BLED Score
HAS-BLED score for estimating 1-year risk of major bleeding in patients on anticoagulation, most commonly for atrial fibrillation, guiding bleeding-risk assessment (score 0–9).
Heart Rate
Calculates heart rate from the number of beats counted over a measured time interval.
HEART Score
HEART score for risk stratification of undifferentiated chest pain in the emergency department, predicting 6-week risk of major adverse cardiac events (MACE).
HELLP Syndrome Criteria (Tennessee)
Assesses the HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low Platelets) using the Tennessee (Sibai) diagnostic criteria: hemolysis (LDH ≥ 600 U/L or schistocytes/low haptoglobin), AST ≥ 70 U/L, and platelets < 100,000/µL. HELLP is a severe form of preeclampsia with substantial maternal and fetal risk.
HOMA-B Calculator
Estimates pancreatic beta-cell function from fasting plasma glucose and fasting serum insulin using the HOMA equation.
HOMA-IR Calculator
Estimates insulin resistance from fasting plasma glucose and fasting serum insulin using the Homeostasis Model Assessment (HOMA) equation.
Hunt and Hess Scale
The Hunt and Hess scale classifies the clinical severity of aneurysmal subarachnoid hemorrhage into five grades based on headache, nuchal rigidity, level of consciousness, and focal deficits. Higher grades predict higher mortality.
Ideal Body Weight
Calculates Ideal Body Weight using the Devine formula.
Insulin Sensitivity
Provides a simple estimate of insulin sensitivity as the reciprocal of HOMA-IR.
KDIGO AKI Staging
Classifies acute kidney injury (AKI) severity using the KDIGO 2012 criteria based on serum creatinine changes and urine output. The highest applicable stage is assigned when multiple criteria are met.
Kt/V (Daugirdas Second Generation spKt/V)
Calculates single-pool Kt/V (spKt/V) for hemodialysis adequacy using the Daugirdas second-generation formula. KDOQI defines a minimum delivered spKt/V of 1.2 per treatment for patients treated three times weekly, with a target of 1.4.
Lean Body Weight
Calculates Lean Body Weight using the Boer formula.
Levothyroxine Dose Calculator
Estimates levothyroxine dose for thyroid hormone replacement, accounting for patient age and cardiac risk factors.
Maddrey Discriminant Function
Predicts severity and prognosis in alcoholic hepatitis.
Magnesium Sulfate Dosing (Preeclampsia/Eclampsia)
Calculates the total 24-hour magnesium sulfate dose for seizure prophylaxis in preeclampsia with severe features or eclampsia using standard intravenous regimens (ACOG 2020): a 4–6 g IV loading dose over 20–30 minutes followed by a 1–2 g/hour maintenance infusion.
Maintenance Fluids
Estimates maintenance fluid rate using a weight-based method.
MDRD GFR Equation
Estimates glomerular filtration rate using the 4-variable MDRD equation.
Mean Arterial Pressure (MAP)
Calculates Mean Arterial Pressure from systolic and diastolic blood pressure.
MELD Score
Model for End-stage Liver Disease (MELD) score for predicting 3-month mortality in patients with advanced liver disease.
MELD-Na Score
Model for End-stage Liver Disease Sodium (MELD-Na) score for predicting 3-month mortality in advanced liver disease.
Metabolic Alkalosis Compensation (Expected PaCO₂)
Calculates the expected arterial PaCO₂ in metabolic alkalosis (PaCO₂ ≈ 40 + 0.6 × (HCO₃ − 24)) to assess whether respiratory compensation is appropriate or whether a concurrent respiratory disorder is present.
Metabolic Syndrome (ATP III Criteria)
Assesses metabolic syndrome using the updated NCEP ATP III criteria, which require at least 3 of 5 components: elevated waist circumference, elevated triglycerides (or treatment), reduced HDL (or treatment), elevated blood pressure (or treatment), and elevated fasting glucose (or treatment).
Modified Centor (McIsaac) Score
The Modified Centor score (McIsaac 1998) estimates the probability of group A streptococcal (GAS) pharyngitis. Four criteria (fever > 38°C, absence of cough, tonsillar exudates, tender anterior cervical adenopathy) score 1 point each, with an age adjustment (3–14 years +1, 15–44 years 0, ≥ 45 years −1); the total is clamped to 0–4. Scores of 0–1 suggest low, 2–3 intermediate, and 4 high GAS probability, guiding rapid antigen testing and treatment decisions.
Modified Rankin Scale
The modified Rankin Scale (mRS) measures the degree of functional disability after a stroke or other neurologic event using six levels from 0 (no symptoms) to 5 (severe disability), plus 6 for death. It is the standard outcome measure in stroke trials.
NAFLD Fibrosis Score
Non-invasive score used to estimate advanced fibrosis in patients with NAFLD/MASLD.
National Early Warning Score 2 (NEWS2)
National Early Warning Score 2 (NEWS2).
NIH Stroke Scale
The National Institutes of Health Stroke Scale quantifies neurologic impairment after acute stroke by scoring 15 examination items (level of consciousness, orientation, commands, gaze, visual fields, facial palsy, motor arm and leg, ataxia, sensory, language, dysarthria, and extinction). The total ranges 0–42; higher scores indicate more severe deficit.
Non-HDL Cholesterol
Calculates non-HDL cholesterol (total cholesterol minus HDL cholesterol). Non-HDL captures all atherogenic apolipoprotein B-containing lipoproteins, including LDL, VLDL, IDL, and remnants, and is a secondary lipid treatment target per ATP III guidelines.
Osmolar Gap
Calculates the osmolar gap as the difference between measured and calculated serum osmolality. An elevated osmolar gap may suggest toxic alcohol ingestion (methanol, ethylene glycol) or other osmotically active substances.
Ottawa SAH Rule
The Ottawa Subarachnoid Hemorrhage Rule identifies patients with acute nontraumatic headache who require CT to rule out SAH. If any of six high-risk findings is present, CT is indicated; if none are present, CT is not required (100% sensitivity).
Oxygen Index
Calculates the Oxygen Index to assess severity of hypoxemic respiratory failure in mechanically ventilated patients.
PaO₂ / FiO₂ Ratio
Calculates the arterial oxygen partial pressure to inspired oxygen fraction ratio for assessment of hypoxemia and ARDS severity.
Parkland Formula
Parkland (Baxter) formula for initial crystalloid resuscitation of adults with thermal burns: 4 mL/kg/%TBSA over 24 hours, with half in the first 8 hours and half over the following 16 hours.
Patient Health Questionnaire-9 (PHQ-9)
The PHQ-9 (Kroenke 2001) screens for and grades the severity of depressive symptoms over the prior two weeks. Nine DSM-based items are each scored 0–3 (total 0–27), with cut-points for minimal, mild, moderate, moderately severe, and severe depression; a score ≥ 10 has ~88% sensitivity and ~88% specificity for major depression. Item 9 screens for suicidal ideation and warrants urgent evaluation when endorsed.
PECARN Minor Head Trauma Rule
Risk-stratifies children with minor blunt head trauma for clinically important traumatic brain injury (ciTBI) using the age-specific PECARN decision rule (Kuppermann 2009). Two separate rules apply for children under 2 years and children 2 years and older; the risk of ciTBI is < 0.02–0.05% when none of the rule's predictors are present.
Pediatric BMI Calculator (BMI-for-Age)
Calculates BMI for children and adolescents (ages 2–20) and classifies weight status using CDC 2000 BMI-for-age percentile references.
Pediatric Early Warning Score (Brighton PEWS)
Scores clinical deterioration risk on pediatric wards using the Brighton Pediatric Early Warning Score (Monaghan 2005): Behavior, Cardiovascular, and Respiratory domains (each 0–3) plus 1 additional point for persistent parent or staff concern, for a total of 0–10. Higher scores trigger escalating observation and urgent review.
Pediatric Glasgow Coma Scale
Age-modified Glasgow Coma Scale for infants and children, using the same eye (1–4) and motor (1–6) components as the adult scale but an age-appropriate verbal response (1–5). Sum ranges 3–15; lower scores indicate more severe impairment of consciousness.
Pediatric Hypotension (PALS) Threshold
Determines the age-based 5th-percentile systolic blood pressure threshold below which hypotension is defined in children (PALS/AAP): < 60 mmHg in term newborns to 1 month, < 70 mmHg in infants 1–12 months, < 70 + (2 × age in years) in children 1–10 years, and < 90 mmHg beyond 10 years. Compares a measured systolic blood pressure against the threshold.
Pediatric Trauma Score (PTS)
Scores pediatric trauma severity across six components (weight, airway, systolic blood pressure, mental status, open wounds, skeletal injury), each scored +2 (minor), +1 (moderate), or −1 (severe), for a total of −6 to +12. Lower scores predict higher mortality and the need for transfer to a pediatric trauma center.
PERC Rule
Pulmonary Embolism Rule-Out Criteria (PERC) for identifying patients in whom PE can be safely ruled out without further testing when clinical pre-test probability is low.
Preeclampsia Criteria (ACOG 2020)
Assesses the diagnostic criteria for preeclampsia and the presence of severe features using ACOG Practice Bulletin No. 222 (2020): hypertension after 20 weeks with proteinuria or end-organ dysfunction, with severe features including BP ≥ 160/110, thrombocytopenia, renal insufficiency, liver involvement, pulmonary edema, and cerebral/visual symptoms.
PSI / PORT Score
Pneumonia Severity Index (PSI / PORT score) for 30-day mortality risk stratification in community-acquired pneumonia to guide site-of-care decisions.
Quantitative Insulin Sensitivity Check Index (QUICKI)
Calculates QUICKI, an index of insulin sensitivity derived from fasting insulin and fasting glucose: QUICKI = 1 / (log10 fasting insulin [µU/mL] + log10 fasting glucose [mg/dL]). Lower values indicate greater insulin resistance; the index is primarily a research and screening tool.
Quick SOFA (qSOFA) Score
Quick Sequential Organ Failure Assessment (qSOFA) for identifying patients at high risk of poor outcomes from suspected infection.
RACE Scale
The RACE (Rapid Arterial oCclusion Evaluation) scale is a prehospital tool that scores 5 items — facial palsy, arm motor, leg motor, gaze deviation, and aphasia/agnosia — on a 0–9 scale. A score of 5 or more suggests a large vessel occlusion stroke.
Renal Failure Index (RFI)
Calculates the renal failure index (RFI), a classic urinary index that uses urine sodium relative to the urine:plasma creatinine ratio to help distinguish prerenal azotemia from acute tubular necrosis (ATN).
Respiratory Compensation Calculator (Expected Bicarbonate)
Estimates the expected serum bicarbonate during acute or chronic respiratory acidosis and alkalosis using the Winters/Merck compensation rules, helping to identify whether a metabolic disturbance is appropriately compensated or a mixed disorder is present.
Revised Cardiac Risk Index (RCRI)
Revised Cardiac Risk Index (Lee index) for estimating the risk of major perioperative cardiac complications (MI, pulmonary edema, VF or primary cardiac arrest, complete heart block) in patients undergoing non-cardiac surgery.
Revised Trauma Score
Revised Trauma Score (RTS) using coded Glasgow Coma Scale, systolic blood pressure, and respiratory rate to triage trauma patients and predict survival.
Rochester Criteria (Febrile Infant)
Risk-stratifies febrile infants aged 0–60 days for serious bacterial infection (SBI) using the Rochester criteria (Jaskiewicz 1994). An infant who meets all seven criteria is considered LOW RISK and can be managed with careful outpatient follow-up; failure to meet any criterion warrants a full sepsis evaluation and admission.
Rockall Score
Predicts mortality and risk of rebleeding after upper gastrointestinal bleeding.
ROX Index
Predicts success of high-flow nasal cannula (HFNC) therapy in acute hypoxemic respiratory failure.
Rumack-Matthew Acetaminophen Nomogram
Determines whether N-acetylcysteine (NAC) treatment is indicated following a single acute acetaminophen (paracetamol) ingestion, based on the serum acetaminophen concentration and time since ingestion.
Serum Osmolality
Calculates the estimated serum osmolality using sodium, glucose, and blood urea nitrogen (BUN). Useful in evaluating electrolyte disorders, dehydration, toxic alcohol ingestion, and calculating the osmolar gap.
Serum-Ascites Albumin Gradient (SAAG)
Calculates the gradient between serum albumin and ascitic fluid albumin to classify ascites as portal hypertensive (SAAG ≥1.1 g/dL) or non-portal hypertensive (SAAG <1.1 g/dL). First-line diagnostic tool for ascites workup.
Shock Index
Calculates Shock Index from heart rate and systolic blood pressure.
SIRS Criteria
Systemic Inflammatory Response Syndrome (SIRS) criteria — the presence of two or more criteria (temperature, heart rate, respiratory rate, white blood cell count) indicates SIRS.
Sodium Deficit
Estimates sodium deficit for hyponatremia correction planning. Helps determine the total amount of sodium needed to raise serum sodium to a target level.
SOFA Score
Sequential Organ Failure Assessment (SOFA) score quantifying six organ systems (respiratory, coagulation, liver, cardiovascular, neurologic, renal) in critically ill patients.
STOP-BANG OSA Screening Score
The STOP-BANG score (Chung 2008/2012) is an eight-item screening tool for obstructive sleep apnea (OSA). Each of the eight items (Snoring, Tiredness, Observed apnea, high blood Pressure, BMI > 35, Age > 50, Neck circumference > 40 cm, male Gender) scores 1 point (total 0–8). Scores of 3–4 indicate intermediate and 5–8 high OSA risk; a score ≥ 3 is highly sensitive for moderate (93%) and severe (100%) OSA and can help rule out disease when negative.
TIMI Risk Score (UA/NSTEMI)
TIMI risk score for unstable angina / non-ST-elevation myocardial infarction, estimating 14-day risk of all-cause mortality, new or recurrent MI, or severe recurrent ischemia requiring urgent revascularization.
Total Cholesterol / HDL Ratio (TC/HDL)
Calculates the total cholesterol to HDL ratio (TC/HDL), a lipid-based cardiovascular risk indicator that compares total cholesterol with the protective HDL fraction.
Transtubular Potassium Gradient (TTKG)
Calculates the transtubular potassium gradient to assess renal potassium handling.
Triglyceride to HDL Ratio (TG/HDL)
Calculates the ratio of fasting triglycerides to HDL cholesterol. A ratio ≥ 3.0 (mg/dL units) has been used as a marker of insulin resistance in overweight non-diabetic adults. The predictive value is ethnicity-dependent and is not reliable in African American populations.
Triglyceride-Glucose (TyG) Index
Calculates the triglyceride-glucose (TyG) index, a surrogate marker of insulin resistance derived from fasting triglycerides and fasting plasma glucose: TyG = ln(TG × FPG / 2) with units in mg/dL. Elevated values indicate greater insulin resistance and higher cardiometabolic risk.
Urine Anion Gap (UAG)
Calculates the urine anion gap: UAG = (urine sodium + urine potassium) − urine chloride. It is used to distinguish renal from extrarenal (gastrointestinal) causes of a normal anion gap (hyperchloremic) metabolic acidosis with hypokalemia and normal renal function.
Urine Osmolal Gap (UOG)
Calculates the urine osmolal gap — the difference between measured and estimated urine osmolality — to detect unmeasured osmoles in the urine (e.g., ethylene glycol, mannitol, or other toxins).
Urine Protein-to-Creatinine Ratio (UPCR)
Calculates the urine protein-to-creatinine ratio (UPCR) from a spot urine sample to estimate 24-hour proteinuria for CKD detection, monitoring, and nephrotic range proteinuria screening.
Waist-to-Hip Ratio
Calculates Waist-to-Hip Ratio to assess central adiposity and cardiovascular risk.
Wells Score (DVT)
Wells criteria for deep vein thrombosis — pre-test clinical probability of DVT to guide D-dimer testing and compression ultrasound.
Wells Score (PE)
Wells criteria for pulmonary embolism — pre-test clinical probability of PE to guide D-dimer testing and imaging.
Westley Croup Score
Scores croup severity using the five-component Westley scale (1978): level of consciousness, cyanosis, stridor, air entry, and retractions, summed from 0–17. Higher scores indicate more severe upper-airway obstruction and impending respiratory failure.
Winter's Formula (Expected PaCO2 in Metabolic Acidosis)
Calculates the expected compensatory respiratory response to a primary metabolic acidosis: expected PaCO2 = 1.5 × HCO3 + 8 ± 2 mmHg. It is used to determine whether the respiratory response is appropriate, inadequate (respiratory acidosis), or excessive (respiratory alkalosis).