Medical Calculators
BMI Percentile Calculator
Work out BMI from height and weight and see how paediatric BMI-for-age percentile bands are defined, with the standard categories explained in full.
Body Surface Area (BSA) Calculator
Calculate body surface area with the Mosteller formula, plus a computed BSA reference grid across heights from 150 to 190 cm and weights to 100 kg.
CHA₂DS₂-VASc Calculator
Work through the CHA2DS2-VASc point scheme letter by letter, with the published annual stroke risk figures from the Friberg registry validation cohort.
Corrected Age Calculator
Adjust a premature baby's chronological age for weeks of missed gestation, with the prematurity adjustment table and a worked developmental example.
Creatinine Clearance Calculator
Estimate creatinine clearance with Cockcroft-Gault, including a computed reference table by age, sex and creatinine, and how it differs from eGFR.
eGFR Calculator
Estimate GFR using the race-free CKD-EPI 2021 creatinine equation, with a computed reference table across age, sex and creatinine plus KDIGO categories.
Heart Attack Risk Calculator
An educational point tally of six cardiovascular risk factors - age, sex, cholesterol, blood pressure, smoking and diabetes - with every weighting shown.
Medication Dosage Calculator
Multiply a mg/kg rate by body weight, with a computed dose reference grid and a breakdown of where weight-based dosing errors actually come from.
MELD Score Calculator
Compute the original 2002 MELD score from bilirubin, INR and creatinine, with worked examples and an explanation of the floor, cap and dialysis rules.
Pediatric Dosage Calculator
Apply Clark's Rule to scale an adult dose by a child's weight, with a computed dose table and a clear account of why the rule has been superseded.
Wells Score Calculator
Score the nine Wells criteria for DVT, including the one criterion that subtracts two points, and see how the low, moderate and high bands are drawn.
The Clinical Formulas Behind Common Risk Scores
Clinical medicine relies on standardized scoring systems to turn patient data into consistent risk assessments — CHA2DS2-VASc for stroke risk in atrial fibrillation, MELD score for liver disease severity, Wells score for clot risk. These calculators apply the exact published formulas behind those clinical tools, intended as an educational and reference resource alongside, not a replacement for, clinical judgment.
Popular Medical Calculators
Eleven tools span kidney function, risk scoring, and dosage:
- eGFR Calculator — estimates kidney filtration rate from creatinine, age, and demographic factors.
- Body Surface Area (BSA) Calculator — calculates BSA from height and weight, commonly used for medication dosing.
- MELD Score Calculator — estimates liver disease severity and transplant priority from lab values.
- CHA2DS2-VASc Calculator — estimates stroke risk in patients with atrial fibrillation based on clinical risk factors.
- Pediatric Dosage Calculator — calculates weight-based medication dosing for pediatric patients.
Why Kidney Function Formulas Keep Getting Updated
eGFR formulas have been revised multiple times as research identified ways to make estimates more accurate and equitable across different patient populations — earlier formulas included a race-based coefficient that has since been removed from major clinical guidelines in favor of race-free equations, reflecting an evolving understanding of how creatinine production and clearance actually relate to demographic factors. This history is a useful reminder that clinical formulas, including the ones in this category, represent current best-practice estimates rather than fixed physical constants, and are periodically revised as medical understanding improves.
Frequently Asked Questions
Are these medical calculators a substitute for a doctor's assessment?
No — they're reference tools that apply the same published formulas used in clinical practice, but any actual medical decision should involve a qualified healthcare provider who has full context on the patient.
Why does pediatric dosing use weight instead of a flat adult dose?
Children's body composition, organ function, and drug metabolism differ substantially from adults and vary by age and weight, so dosing scaled to body weight (or body surface area for some drugs) is safer and more accurate than a fixed dose.
Explore More
Looking for general health tracking instead of clinical scores? See the Health Calculators, or check dental-specific dosing in the Dental Calculators.