Creatinine clearance calculator using the Cockcroft-Gault equation
For healthcare professionals and students. Check results against your local protocols and clinical judgement; this tool does not give medical advice.
This creatinine clearance calculator estimates CrCl in mL/min with the Cockcroft-Gault equation, the estimate most drug labels and renal dose tables have historically used. Enter age, sex, serum creatinine in mg/dL or µmol/L, weight and height, and it shows CrCl with actual, ideal and adjusted body weight side by side, with the full working, so the weight choice your protocol asks for is visible rather than hidden.
Pharmacists, prescribers, nurses and students use it to check renal dose adjustments and to understand why the same patient can get different answers. Everything runs in your browser.
How to use the Creatinine Clearance Calculator (Cockcroft-Gault)
- Enter the age in years and choose the sex.
- Enter the serum creatinine and choose mg/dL or µmol/L.
- Enter the actual body weight (kg or lb) and the height (cm or inches).
- Choose the weight used in the equation: actual, ideal, adjusted, or the BMI-based suggestion.
- Read the CrCl, compare the three weights in the boxes below it, and check the warnings before using the number.
Creatinine Clearance Calculator (Cockcroft-Gault) features
Three weights at once
CrCl with actual, ideal (Devine) and adjusted body weight, so the effect of the choice is obvious.
SI and conventional units
Creatinine in mg/dL or µmol/L (1 mg/dL = 88.4 µmol/L), weight in kg or lb, height in cm or inches.
BMI-based suggestion
Optional weight choice from the BMI categories in Winter et al. 2012, clearly labelled.
Full working
The equation, ideal and adjusted weight and unit conversions are written out with your numbers.
Plausibility checks
Warns about children, unit mix-ups, extreme weights or heights, very low creatinine and unstable kidney function.
The Cockcroft-Gault formula
Published by Cockcroft DW and Gault MH, Nephron 1976;16(1):31–41, the equation is CrCl (mL/min) = (140 − age) × weight (kg) ÷ (72 × serum creatinine in mg/dL), multiplied by 0.85 for women. With creatinine in µmol/L, divide by 88.4 first (creatinine’s molar mass is 113.12 g/mol, so 1 mg/dL = 88.4 µmol/L).
Worked example: a 60-year-old man weighing 72 kg with a creatinine of 1.0 mg/dL (88.4 µmol/L) has (140 − 60) × 72 ÷ (72 × 1.0) = 80 mL/min; a woman with the same values has 80 × 0.85 = 68 mL/min. The result is not normalised to 1.73 m² body surface area.
Which body weight should you use?
The original equation used actual weight, and the choice matters most in obesity. The National Kidney Foundation’s Cockcroft-Gault page (checked 19 October 2026) notes that weight is applied inconsistently between clinicians and institutions and that no single weight is accurate across all body sizes. Follow your local protocol or the drug’s label.
| Weight | Formula | Winter et al. 2012 finding |
|---|---|---|
| Ideal body weight (Devine 1974) | Men 50 kg, women 45.5 kg, + 2.3 kg per inch over 5 ft | Most accurate in normal-weight patients (BMI 18.5–24.9) |
| Actual body weight | Weight on the scale | Most accurate in underweight patients (BMI < 18.5) |
| Adjusted body weight | IBW + 0.4 × (actual − IBW) | Most accurate in overweight and obese patients (BMI ≥ 25) |
Cockcroft-Gault, MDRD and CKD-EPI
MDRD and CKD-EPI estimate glomerular filtration rate normalised to 1.73 m² (mL/min/1.73 m²) and are used to stage chronic kidney disease. Cockcroft-Gault estimates creatinine clearance in mL/min for the individual, which is why many dose tables were built on it. The numbers are not interchangeable, so use the one the dosing reference was written for.
Two further cautions from the NKF page: most laboratories now report creatinine traceable to isotope dilution mass spectrometry (IDMS), which reads lower than older methods, so today’s Cockcroft-Gault values run higher than those in older pharmacokinetic studies; and the 15% reduction for women was estimated rather than measured. Any creatinine-based estimate needs a stable creatinine and is unreliable in acute kidney injury, dialysis, amputation, pregnancy or extreme muscle mass.
Creatinine Clearance Calculator (Cockcroft-Gault) FAQ
How is creatinine clearance calculated?
With the Cockcroft-Gault equation: (140 − age) × weight in kg ÷ (72 × creatinine in mg/dL), times 0.85 for women. The creatinine clearance calculator above shows each step with your numbers.
How do I convert creatinine from µmol/L to mg/dL?
Divide by 88.4. For example 106 µmol/L ÷ 88.4 = 1.20 mg/dL. To go the other way, multiply mg/dL by 88.4.
Should I use ideal, actual or adjusted body weight?
It depends on your protocol and the drug. Winter et al. (Pharmacotherapy 2012;32(7):604–612) found ideal weight most accurate in normal-weight patients, actual weight in underweight patients and adjusted weight (factor 0.4) in overweight and obese patients. The calculator shows all three.
Is creatinine clearance the same as eGFR?
No. eGFR from MDRD or CKD-EPI is normalised to 1.73 m² body surface area and is used to stage kidney disease; Cockcroft-Gault CrCl is in mL/min and is the basis of many older drug-dosing tables.
Can I use this for children?
No. Cockcroft-Gault was developed in adults. Children need a paediatric equation, and the tool warns when the age is under 18.
What is ideal body weight?
In the Devine formula it is 50 kg for men and 45.5 kg for women plus 2.3 kg for each inch over 5 feet. There is also a general ideal weight calculator that compares several formulas.