Estimates creatinine clearance with the Cockcroft-Gault equation, using actual, ideal or adjusted body weight.
Result
Enter age, sex, weight and creatinine.
Sources
2 studies
2
studies
15,283
citations
1,821
PubMed papers
Evidence
Known limitations
A formula for creatinine clearance from age, weight and serum creatinine in adult men, taken as 15% less in women. Predicted values correlated with the mean of two measured 24-hour clearances at r = 0.83 in 236 patients; the authors note that age and weight must be included for a reasonable prediction.
In 3,678 patients with stable kidney function and a 24-hour urine collection, the Cockcroft-Gault estimate was unbiased with actual weight in underweight patients and with ideal weight at normal weight; for overweight and obese patients, adjusted weight (factor 0.4) was least biased and most accurate. Using the measured creatinine was less biased than rounding it up to 0.8 or 1.0 mg/dL.
Pharmacotherapy: Journal Metrics Score 2.4, Q1 · cited 198 times
The original paper has been cited 15,283 times, and 1,821 PubMed articles mention the Cockcroft-Gault equation in their title or abstract. Citation counts from OpenAlex and article counts from PubMed, retrieved November 9, 2026. Journal Metrics Scores and quartiles are from this site’s current release; follow the journal name for details.
After the result
Before using the result · Drug dosing · Below 30 mL/min
Check the creatinine is stable and the weight fits the patient. Use the label’s own thresholds. Severely reduced: review every renally cleared drug.
Next steps
Avoid common errors
7 common errors to avoid
and 5 more
When the estimate misleads
1Obesity
With actual weight the equation overestimates clearance in obesity: in the first example below, 116 mL/min with actual weight against 73 with ideal and 90 with adjusted weight.
2Low muscle mass
A frail older person with a creatinine of 0.5 to 0.6 mg/dL may have a lower clearance than the equation gives. Rounding the creatinine up was not more accurate in Winter 2012; interpret the result with the patient in mind.
3Unstable creatinine
The equation needs a steady-state creatinine. In acute kidney injury, or soon after dialysis, it does not reflect current function.
4Dialysis
Do not use in people on dialysis: their creatinine reflects dialysis, not their own kidney clearance.
5Creatinine units
The formula uses mg/dL. A creatinine of 109 entered as mg/dL instead of µmol/L gives a result near zero; check the unit beside the box.
6Not an eGFR
The result is in mL/min, not mL/min/1.73 m². Do not use it to stage chronic kidney disease, and do not mix it with eGFR thresholds.
7Amputation, pregnancy, extremes of size
Weight-based estimates are least reliable after limb loss, in pregnancy and at extremes of body size or muscle mass. A measured clearance or cystatin C may help.
Formula
(140 − age) × weight / (72 × creatinine), × 0.85 for women; weight actual, ideal or adjusted.
(140 − age) × wt / (72 × Cr)
(140 − age) × weight / (72 × creatinine), × 0.85 for women; weight actual, ideal or adjusted.
Formula and weights
| Value | Formula |
|---|---|
| Creatinine clearance | (140 − age) × weight (kg) / (72 × creatinine, mg/dL); × 0.85 for women |
| Ideal weight (Devine) | 50 kg (men) or 45.5 kg (women) + 2.3 kg per inch over 5 feet |
| Adjusted weight | ideal + 0.4 × (actual − ideal) |
| Choice by BMI (Winter 2012) | below 18.5: actual; 18.5 to 24.9: ideal (or actual, if lower); 25 or more: adjusted |
| mL/min | Meaning |
|---|---|
| 90 mL/min or more | 90 mL/min or more: clearance is not reduced. Very high values, as in young critically ill patients, may mean faster drug clearance than usual; the equation can miss this, and a measured clearance is more reliable. |
| 60 to 89 mL/min | Between 60 and 89 mL/min: mildly reduced clearance, which is common with age. |
| 30 to 59 mL/min | Between 30 and 59 mL/min: moderately reduced clearance. Labels often set thresholds in this range, such as 30 or 50 mL/min. |
| 15 to 29 mL/min | Between 15 and 29 mL/min: severely reduced clearance. Many drugs cleared by the kidney need a change at this level; check the label and a pharmacist. |
| Below 15 mL/min | Below 15 mL/min: very low clearance. Check how each drug label handles this range; many advise against use or give separate dialysis guidance. |
Cockcroft and Gault 1976
Weight
Height below 5 feet
Units
Test cases
3 published cases, each also a test case
3 published cases; the calculator reproduces every result.
Worked examples
A 42-year-old man, 170 cm and about 105 kg (BMI 36.3), was on extracorporeal support for severe pneumonia with a creatinine of 109 µmol/L. The report calculates a clearance of about 73 mL/min with ideal weight (66 kg) and 90 mL/min with adjusted weight (82 kg), and did not use actual weight.
“retrospective Cockcroft-Gault creatinine clearance was approximately 73 mL/min using ideal body weight (66 kg) and 90 mL/min using adjusted body weight (82 kg); actual weight was not used”
The calculator gives ideal weight 65.9 kg and adjusted 81.6 kg, and clearances of 73 and 90 mL/min, as in the report. With actual weight it would be 116 mL/min. Creatinine had fallen from 137 µmol/L on admission, so it was not at steady state; choosing by BMI would use adjusted weight here (90 mL/min).
Entered as: Age: 42 years; Sex: Male; Weight: 105 kg; Serum creatinine: 109 µmol/L; Height: 170 cm; Weight in the equation: Ideal weight (Devine).
Source: Jiang F et al., Front Med (Lausanne) 2026 (PubMed · Free full text · DOI)
An 89-year-old man admitted with dehydration and poor appetite later developed a bloodstream infection; at the start of treatment he weighed an estimated 36.5 kg, with a creatinine of 0.54 mg/dL. The report gives a Cockcroft-Gault clearance of 47.9 mL/min.
“His estimated weight at this time was 36.5 kg, his creatinine level was 0.54 mg/dL, and his creatinine clearance, calculated using the Cockcroft-Gault equation, was 47.9 mL/min.”
The calculator gives 47.9 before rounding. A creatinine this low in a very thin older man reflects low muscle mass, so the clearance may still be overestimated.
Entered as: Age: 89 years; Sex: Male; Weight: 36.5 kg; Serum creatinine: 0.54 mg/dL; Weight in the equation: Actual weight.
Source: Date J et al., J Pharm Health Care Sci 2025 (PubMed · Free full text · DOI)
An 88-year-old woman with atrial fibrillation weighed 47.2 kg. Her creatinine was 0.98 mg/dL, and the report gives a Cockcroft-Gault clearance of 29.5 mL/min (about 30 mL/min), against an eGFR of 40.5 mL/min/1.73 m².
“Serum creatinine was 0.98 mg/dL, the estimated glomerular filtration rate was 40.5 mL/min/1.73 m², and the Ccr calculated using the Cockcroft-Gault equation was 29.5 mL/min.”
The calculator gives 29.6 before rounding (29.5 in the report). The clearance is lower than the eGFR, which is indexed to 1.73 m² of body surface: in a small older woman the two can fall on different sides of a drug threshold.
Entered as: Age: 88 years; Sex: Female; Weight: 47.2 kg; Serum creatinine: 0.98 mg/dL; Weight in the equation: Actual weight.
Source: Takai K et al., Cureus 2026 (PubMed · Free full text · DOI)
FAQ
7 questions and answers
and 5 more answers
Questions
Creatinine clearance (mL/min) = (140 − age) × weight (kg) / (72 × serum creatinine in mg/dL), multiplied by 0.85 for women. With creatinine in µmol/L, divide it by 88.42 first. A 42-year-old man weighing 66 kg with a creatinine of 1.23 mg/dL has (98 × 66) / (72 × 1.23) = 73 mL/min.
Cockcroft and Gault used actual weight. In 3,678 patients with a measured 24-hour clearance, Winter and colleagues (2012) found actual weight least biased in underweight patients, ideal weight at a normal BMI, and adjusted weight (ideal + 0.4 × excess) when overweight or obese. The calculator lets you choose, or pick by BMI, and shows the result with all three when you enter the height.
Ideal weight (Devine) is 50 kg for men or 45.5 kg for women, plus 2.3 kg for every inch over 5 feet (152.4 cm). Adjusted weight = ideal + 0.4 × (actual − ideal). For a man 170 cm tall weighing 105 kg: ideal 65.9 kg, adjusted 81.6 kg.
No. Cockcroft-Gault estimates creatinine clearance in mL/min for the person’s actual size. eGFR equations such as CKD-EPI estimate the glomerular filtration rate in mL/min per 1.73 m² of body surface, and are what KDIGO uses to stage chronic kidney disease. In a small older woman the clearance can be well below the eGFR, as in one of the examples below.
Rounding up is a common habit in older adults with low muscle mass, but Winter and colleagues found the measured creatinine unbiased on average in patients 65 and over, and more accurate than a value rounded up to 0.8 or 1.0 mg/dL. In a frail patient, remember that a very low creatinine may still overestimate clearance.
Many older drug labels set their kidney thresholds from studies that estimated kidney function with Cockcroft-Gault, so the label’s cut-offs are in creatinine clearance. This page gives the clearance only; check the label or a pharmacist for any dose.
No. It assumes the creatinine is stable. When kidney function changes quickly, the creatinine lags behind, and the calculated clearance does not reflect the current function.
Further reading
6 references with PubMed and DOI links
6
references
3
free full text
From Cockcroft DW et al., Nephron 1976 to the newest case reports.
References
Contributed by Dr. Meng Zhao (MD · Former Neurosurgeon · Medical AI Researcher), from the original publications listed here. Last updated November 9, 2026. LinkedIn
The calculator code is tested against every worked example on this page before each release.
This calculator supports, and does not replace, clinical judgment. It is meant for healthcare professionals and is not medical advice for patients. Report an error through the contact page.
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