Free UK clinical calculators
Fast, evidence-linked tools for everyday prescribing and risk estimation. Every calculator shows its formula, primary citation, UK (NICE/BNF) practice note and caveats.
Patient review (anonymous)
Enter parameters → CrCl/eGFR → add medications for renal & interaction checks → infection guidance with NICE and local links. No identifiers, browser-only.
Renal
Creatinine Clearance (Cockcroft–Gault)
Estimates creatinine clearance for drug dosing from age, sex, weight and serum creatinine, with actual, ideal or adjusted body weight options.
eGFR — CKD-EPI 2021 (race-free creatinine)
Estimates GFR using the 2021 CKD-EPI creatinine equation, refitted without a race coefficient (ASN/NKF recommendation in the US).
eGFR — CKD-EPI 2009 (creatinine)
Estimates GFR using the original 2009 CKD-EPI creatinine equation — the basis of eGFR reported by UK laboratories.
eGFR — MDRD (4-variable, IDMS)
Estimates GFR using the 4-variable MDRD Study equation re-expressed for standardised (IDMS-traceable) creatinine. Largely superseded by CKD-EPI.
eGFR — Revised Schwartz (bedside, paediatric)
Estimates GFR in children aged 1–16 years from height and serum creatinine (revised 'bedside' Schwartz equation, 2009).
Risk scores
NEWS2 (National Early Warning Score 2)
The Royal College of Physicians' aggregate score for detecting deterioration in acutely ill adults — the NHS standard.
CHA₂DS₂-VASc — stroke risk in atrial fibrillation
Estimates annual stroke/thromboembolism risk in non-valvular atrial fibrillation to guide anticoagulation decisions.
HAS-BLED — bleeding risk on anticoagulation
Estimates major bleeding risk in patients with atrial fibrillation considered for anticoagulation, highlighting modifiable risk factors.
Conversions
Corticosteroid Equivalence Conversion
Converts between oral corticosteroids using standard anti-inflammatory equivalence (hydrocortisone 20 mg basis).
Opioid Conversion & Morphine Milligram Equivalents (MME)
Calculates total daily morphine milligram equivalents (CDC 2022 factors) and unadjusted equianalgesic doses between oral opioids.
Benzodiazepine Equivalence Conversion (diazepam equivalents)
Converts between benzodiazepines and Z-drugs using approximate diazepam equivalents (Ashton Manual basis).
Electrolytes
Endocrine
Neurology
Anaesthesia
Neonatal
Body size
Ideal & Adjusted Body Weight (Devine)
Calculates Devine ideal body weight and, when actual weight is provided, adjusted body weight for dosing in obesity.
Body Mass Index (BMI)
Calculates BMI with WHO weight categories, plus the healthy weight range for the given height.
Body Surface Area (Mosteller & Du Bois)
Calculates body surface area using the Mosteller equation (UK standard) with the Du Bois equation for comparison.