# Creatinine Clearance Calculator

Calculate your creatinine clearance and kidney function using the Cockcroft-Gault equation. Estimate GFR from serum creatinine, age, weight, and sex.

## What this calculates

Creatinine clearance is a key indicator of kidney function used to stage chronic kidney disease and adjust medication dosages. This calculator uses the Cockcroft-Gault equation, one of the most widely used formulas in clinical practice, to estimate your kidney function from a blood test result.

## Inputs

- **Sex** — options: Male, Female
- **Age** (years) — min 18, max 110
- **Body Weight** (kg) — min 30, max 250
- **Serum Creatinine** (mg/dL) — min 0.1, max 20 — From your blood test results

## Outputs

- **Creatinine Clearance (CrCl)** (mL/min) — Estimated creatinine clearance (Cockcroft-Gault)
- **Kidney Function Stage** — formatted as text — CKD stage based on estimated GFR
- **Clinical Interpretation** — formatted as text — What your creatinine clearance means

## Details

The Cockcroft-Gault equation estimates creatinine clearance (CrCl) as a surrogate for glomerular filtration rate (GFR), which measures how effectively the kidneys filter waste from the blood. The formula accounts for age (kidney function naturally declines with age), body weight (larger bodies produce more creatinine), sex (women produce less creatinine due to lower muscle mass), and serum creatinine levels.

The formula is: CrCl = [(140 - age) x weight(kg)] / [72 x serum creatinine(mg/dL)], multiplied by 0.85 for women. Normal creatinine clearance is approximately 90-120 mL/min for young adults and decreases by about 1 mL/min per year after age 40.

Creatinine clearance is used clinically for two primary purposes: staging chronic kidney disease (CKD) and adjusting medication dosages. Many drugs are cleared by the kidneys, and impaired kidney function leads to drug accumulation and potential toxicity. This is why drug prescribing information often includes dose adjustments based on CrCl. This calculator is for educational purposes only and should not replace professional medical evaluation.

## Frequently Asked Questions

**Q: What is a normal creatinine clearance?**

A: Normal creatinine clearance is approximately 90-140 mL/min for men and 80-125 mL/min for women. Values decline naturally with age, decreasing by approximately 1 mL/min per year after age 40. A value below 60 mL/min is generally considered clinically significant and indicates moderate kidney impairment. Values below 15 mL/min indicate kidney failure. Your doctor interprets results in context with other tests and your medical history.

**Q: What is the difference between CrCl and GFR?**

A: Creatinine clearance (CrCl) and glomerular filtration rate (GFR) are related but not identical. GFR is the actual rate at which blood is filtered by the kidneys. CrCl estimates GFR using serum creatinine as a marker but tends to slightly overestimate true GFR because some creatinine is secreted by the kidney tubules. The Cockcroft-Gault equation estimates CrCl, while the CKD-EPI and MDRD equations estimate GFR directly. For drug dosing, Cockcroft-Gault CrCl remains the standard.

**Q: When is the Cockcroft-Gault equation less accurate?**

A: The Cockcroft-Gault equation is less accurate for: very obese patients (it overestimates), very lean or cachectic patients (it underestimates), patients with unstable kidney function (rapidly changing creatinine), pregnant women, people with extremes of muscle mass (bodybuilders or amputees), and the very elderly. In these cases, alternative methods such as 24-hour urine collection or the CKD-EPI equation may be more appropriate.

**Q: Why does my doctor check creatinine clearance?**

A: Doctors check creatinine clearance to assess kidney function, which is important for: detecting chronic kidney disease early, monitoring progression of known kidney disease, adjusting medication doses (many drugs require lower doses with impaired kidneys), evaluating fitness for certain procedures or contrast dye use, and screening patients with conditions that affect kidneys like diabetes and hypertension. Regular monitoring helps catch kidney decline before symptoms appear.

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Source: https://vastcalc.com/calculators/health/creatinine-clearance
Category: Health & Fitness
Last updated: 2026-04-21