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Creatinine Clearance Calculator

Estimate creatinine clearance with the Cockcroft-Gault equation using actual, ideal or adjusted body weight, in mg/dL or µmol/L.

Patient and laboratory values

72.9 mL/min
Cockcroft-Gault CrCl
70.0 kg
Weight used
70.5 kg
Devine IBW
—
Normalised

Cockcroft-Gault creatinine clearance

72.9 mL/min

60–89 mL/minMildly reduced. Very few drug labels adjust in this band.
(140 − age) × weight ÷ (72 × Scr)(140 − 65) × 70.0 ÷ (72 × 1.00) = 72.92
Weight basisactual body weight
Serum creatinine1.00 mg/dL = 88 µmol/L
Du Bois BSA1.85 m²
Normalised to 1.73 m²— (turn the option on and enter a height)

Worked check: a 70-year-old man weighing 70 kg with a creatinine of 1.0 mg/dL gives (140 − 70) × 70 ÷ (72 × 1.0) = 68.1 mL/min, the value published in every Cockcroft-Gault reference; the same patient as a woman is 68.1 × 0.85 = 57.9 mL/min.

Which number does a drug label want?

FigureValueWhat it is for
Cockcroft-Gault CrCl72.9 mL/minAn absolute clearance in mL/min, not indexed to body surface area. Most drug licences, direct oral anticoagulant dose bands and renal dosing tables were written against this equation, which is why it survives despite being from 1976.
Normalised CrCl—The same clearance rescaled to a standard 1.73 m² body, so it can be compared with a reported eGFR. Useful for staging conversations, not for dosing.
Laboratory eGFRsee the eGFR toolCKD-EPI 2021 is what your laboratory reports and what KDIGO staging uses. It is a different equation answering a different question — this tool is its drug-dosing counterpart, not a replacement.

Estimates only, not medical advice — never choose or adjust a drug dose from this page. Cockcroft-Gault was fitted in 1976 on 249 mostly male hospital patients using a non-standardised creatinine assay, so it systematically over-estimates clearance in people with low muscle mass and in the very elderly, and modern IDMS-standardised creatinine values push it further out. It assumes a steady state and is unreliable in acute kidney injury, in pregnancy, after amputation, in advanced liver disease and where drugs such as trimethoprim or cimetidine block tubular creatinine secretion. Which body weight to use is a matter of local protocol, not consensus, and can change the answer by 30% or more — check your pharmacy guideline.

What is the Creatinine Clearance Calculator?

Cockcroft-Gault estimates creatinine clearance as (140 − age) × weight in kilograms, divided by 72 × serum creatinine in mg/dL, multiplied by 0.85 for women. It gives an absolute clearance in mL/min, which is what most drug labels are written against.

  • Cockcroft-Gault with actual, Devine ideal or adjusted body weight
  • Creatinine entered in mg/dL or µmol/L with automatic conversion
  • Optional normalisation to mL/min/1.73 m² using Du Bois body surface area
  • Renal dosing bands at 90, 60, 30 and 15 mL/min
  • A comparison table explaining which figure a drug label expects
  • Entirely client-side — patient values never leave your device

How to use the Creatinine Clearance Calculator

  1. 1

    Choose mg/dL or µmol/L and enter the serum creatinine — the tool converts at 88.4 µmol/L per mg/dL.

  2. 2

    Enter the patient's age and sex; women take the 0.85 multiplier automatically.

  3. 3

    Choose metric or imperial units and enter weight, plus height if you want ideal or adjusted body weight.

  4. 4

    Select which body weight the equation should use: actual, Devine ideal, or adjusted.

  5. 5

    Optionally tick BSA normalisation, then read the clearance, the dosing band and the full working.

About the Creatinine Clearance Calculator

The ByteTools Creatinine Clearance Calculator applies the Cockcroft-Gault equation, the estimate that most drug licences, anticoagulant dose bands and renal dosing tables were originally written against. It accepts creatinine in mg/dL or µmol/L, lets you dose off actual, Devine ideal or adjusted body weight, and can normalise the answer to mL/min/1.73 m² so it can be compared with a reported eGFR.

It is deliberately presented as the drug-dosing counterpart to a laboratory eGFR rather than a replacement for it, and the comparison table spells out which figure a given reference actually wants. Every result prints the substitution performed, including which body weight was used and what that weight was.

All arithmetic runs in your browser and no value is uploaded or stored. These are estimates for education and cross-checking only, not medical advice — never choose or adjust a drug dose from a web page, and check every number against your own pharmacy guideline.

Frequently asked questions

What is the Cockcroft-Gault formula?

Creatinine clearance in mL/min equals (140 minus age in years) times weight in kilograms, divided by 72 times serum creatinine in mg/dL, then multiplied by 0.85 if the patient is female. A 70-year-old man weighing 70 kg with a creatinine of 1.0 mg/dL gives 68 mL/min.

What is the difference between creatinine clearance and eGFR?

Cockcroft-Gault gives an absolute clearance in mL/min for that specific body, while a laboratory eGFR such as CKD-EPI 2021 is indexed to a standard 1.73 m² body surface area. Drug labels and dose bands were mostly written against Cockcroft-Gault; kidney disease staging uses eGFR.

Which body weight should I use in Cockcroft-Gault?

There is no universal answer. Many pharmacy protocols use actual weight when it is close to ideal, and switch to ideal or adjusted body weight when the patient is substantially above it, because fat contributes little to creatinine production. The choice can change the answer by 30% or more, so follow local policy.

How do I convert creatinine from µmol/L to mg/dL?

Divide µmol/L by 88.4, the conversion constant derived from creatinine's molar mass of 113.12 g/mol. So 88.4 µmol/L is 1.0 mg/dL and 176.8 µmol/L is 2.0 mg/dL. This calculator handles the conversion automatically when you switch units.

Why does Cockcroft-Gault over-estimate clearance in the elderly?

It infers creatinine production from age and weight, and it was fitted in 1976 on a mostly male hospital population using a non-standardised assay. Anyone with low muscle mass — the frail elderly, amputees, people with advanced cachexia — produces less creatinine, so the equation reads their kidneys as better than they are.

Can I use it in acute kidney injury?

No. Every creatinine-based estimate assumes a steady state. During acute kidney injury the creatinine is still climbing and lags real filtration by a day or more, so the calculated clearance will substantially overstate kidney function at the moment you need it most.

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