Medical Calculators for Clinicians

Free medical calculators for clinicians from 2 Minute Medicine: bedside clinical scores, and the evidence math you need to read a clinical trial. Each one shows the formula, how to read the result and the study behind it.

Clinical scores

Risk and severity scores used at the bedside, each next to the landmark study that introduced it.

• CardiologyCHA₂DS₂-VASc scoreStroke risk in atrial fibrillation, to guide the decision on anticoagulation.Open the calculator →
• HepatologyChild-Pugh scoreSeverity and prognosis of cirrhosis in chronic liver disease, class A to C.Open the calculator →
• HepatologyMELD scorePredicted survival in end-stage liver disease from routine lab values.Open the calculator →
• Critical careMean arterial pressure (MAP)MAP from systolic and diastolic blood pressure, with how to read it.Open the calculator →
• CardiologyCHADS₂ scoreThe original stroke risk score for atrial fibrillation, with stroke rates by score.Open the calculator →
• CardiologyHAS-BLED scoreOne-year risk of major bleeding in atrial fibrillation, and what to correct.Open the calculator →
• CardiologyHEART scoreRisk of a major cardiac event within 6 weeks in emergency department chest pain.Open the calculator →
• CardiologyRevised Cardiac Risk IndexLee index: risk of major cardiac complications after noncardiac surgery.Open the calculator →
• HematologyWells score for DVTClinical probability of deep vein thrombosis, two-tier and three-tier.Open the calculator →
• PulmonologyWells score for PEClinical probability of pulmonary embolism and the next diagnostic step.Open the calculator →
• PulmonologyCURB-65 score30-day mortality in community-acquired pneumonia, and where to treat.Open the calculator →
• NeurologyABCD2 scoreEarly stroke risk after a transient ischemic attack.Open the calculator →
• Emergency medicineCanadian CT Head RuleWhich adults with minor head injury need a CT.Open the calculator →
• Emergency medicineCanadian C-Spine RuleWhich alert trauma patients need cervical spine imaging.Open the calculator →
• Emergency medicineOttawa ankle rulesWhether an ankle or foot injury needs X-rays.Open the calculator →
• PediatricsPECARN head injury ruleCT, observation or no CT for children with minor head trauma.Open the calculator →
• PediatricsKocher criteriaSeptic arthritis versus transient synovitis of the hip in children.Open the calculator →
• PediatricsBacterial Meningitis ScoreChildren with CSF pleocytosis at very low risk of bacterial meningitis.Open the calculator →
• GastroenterologyRockall scoreRisk of rebleeding and death after upper GI bleeding.Open the calculator →
• GastroenterologyHarvey-Bradshaw IndexCrohn disease activity from the previous day.Open the calculator →
• NephrologyCreatinine clearanceCockcroft-Gault, for renal drug dosing, with ideal and adjusted weight.Open the calculator →

Evidence math

Biostatistics calculators for journal club, exams and reading trials, with worked examples from studies we covered.

• Evidence mathOdds ratioOdds ratio from a 2×2 table, with its confidence interval and P value.Open the calculator →
• Evidence mathRelative riskRelative risk with its 95% CI, absolute and relative risk reduction, and NNT.Open the calculator →
• Evidence mathNNT and NNHNumber needed to treat or harm from event counts, two risks or a ratio.Open the calculator →
• Evidence mathSensitivity and specificitySensitivity, specificity, PPV, NPV and likelihood ratios for a diagnostic test.Open the calculator →
• Evidence mathConfidence intervalsWilson, exact and Wald confidence intervals for a proportion.Open the calculator →
• Evidence mathSample sizeParticipants per group to compare two proportions or two means.Open the calculator →
• Evidence mathHazard ratio to absolute riskWhat a hazard ratio means in absolute terms, with the NNT.Open the calculator →
• Evidence mathAll Evidence Math toolsFormulas, worked trial examples and common mistakes, in one place.See all tools →

For health care professionals. These calculators support clinical judgment and do not replace it.