HesapHanem

Cockcroft-Gault Adjusted Body Weight Calculator

Enter age, weight, height, sex and serum creatinine to estimate creatinine clearance.

How it is calculated

Age is in years, weight in kg, height in cm and serum creatinine in mg/dL. The tool first finds the Devine ideal body weight: IBW = 50 + 2.3 × (height in inches − 60) kg for men, or 45.5 instead of 50 for women, with inches = cm ÷ 2.54. If the actual weight is above the IBW, it uses the adjusted weight ABW = IBW + 0.4 × (weight − IBW); if the actual weight is at or below the IBW, the actual weight is used. Then CrCl = (140 − age) × ABW ÷ (72 × creatinine), multiplied by 0.85 for women. Results are in mL/min and kg with one decimal. Anything other than "female" is treated as male. Age, weight, height and creatinine must all be above zero and the age below 140; otherwise no result is shown. This is an estimate and not clinical advice.

Worked example

A 65-year-old man, 100 kg, 170 cm tall, serum creatinine 1.2 mg/dL. Height in inches: 170 ÷ 2.54 = 66.93. IBW: 50 + 2.3 × (66.93 − 60) = 65.9 kg. Since 100 kg is above the IBW, ABW = 65.9 + 0.4 × (100 − 65.9) = 79.6 kg. CrCl = (140 − 65) × 79.6 ÷ (72 × 1.2) = 5,970 ÷ 86.4, about 69.1 mL/min. For a woman with the same values, the result is multiplied by 0.85 and her IBW is lower, giving 56.7 mL/min.

Try this example →

Common mistakes

  • Entering creatinine in µmol/L. The field expects mg/dL, and a value like 106 would make the clearance almost zero.
  • Entering height in inches or metres; it must be centimetres.
  • Entering weight in pounds; it must be kilograms.
  • Using the actual weight for an obese patient. This tool already applies the adjusted weight, so do not pre-adjust the weight before entering it.
  • Leaving the sex on the default. The female factor of 0.85 and the lower IBW are applied only when female is chosen, so a woman entered as male gets an overestimate.

Sources

About this calculator

The Cockcroft-Gault equation estimates creatinine clearance (a proxy for kidney function/glomerular filtration rate) from age, weight, sex, and serum creatinine. In overweight or obese patients, however, using actual body weight overestimates renal function because excess fat mass doesn't contribute proportionally to creatinine production, so this calculator first computes the Devine ideal body weight (IBW) from height and sex, then uses an adjusted body weight — a weighted blend of IBW and actual weight — in place of raw weight in the Cockcroft-Gault formula.

This adjusted-weight approach is standard practice among pharmacists, nephrologists, and hospital clinicians when dosing renally-cleared medications (such as certain antibiotics, anticoagulants, and chemotherapy agents) for heavier patients, since using unadjusted actual weight in these cases can lead to overdosing and using ideal weight alone can underestimate true clearance — the adjusted figure balances both to better reflect real renal drug clearance.

Was this helpful?

You can pick up to 3 reactions.

Comments (1)

  • Editorial team

    This estimate swings hard with creatinine, so confirm the lab unit before anything else. A 65-year-old man, 170 cm and 100 kg, comes out at 69.1 mL/min with creatinine 1.2 mg/dL, but 138.1 mL/min at 0.6. The adjusted weight is applied to any actual weight above ideal weight, not only to clearly obese patients. Dosing decisions belong with a pharmacist or physician. If your result looks off, post your inputs and units so other readers can compare.

Popular calculators

Loan Calculator

Monthly payment, total interest and full amortization schedule.

Percentage Calculator

Percent change, percent of, and ratio calculations.

Discount Calculator

Calculate final price, savings, and discount amount.

BMI Calculator

Body mass index from height and weight (metric or imperial).

Age Calculator

Compute your exact age in years, months and days from a birth date.

Compound Interest Calculator

Calculate the final amount and interest earned with compounding.

All Calculators