Creatinine clearance estimates how many millilitres of blood your kidneys filter per minute, calculated from age, weight, sex and blood creatinine with the Cockcroft-Gault equation. Normal is roughly 90–140 mL/min for men and 80–125 for women, declining with age. An eGFR below 60 for three months defines chronic kidney disease.
Your kidneys’ filtering power is measured by two closely related numbers: creatinine clearance (CrCl) and the glomerular filtration rate (GFR). Both estimate how many millilitres of blood your kidneys clean per minute, both are calculated from a simple blood test — and the difference between them genuinely matters, because one is used to stage kidney disease and the other to dose medications. This calculator estimates creatinine clearance with the Cockcroft-Gault equation, and the guide below explains both systems honestly.
Calculate your estimate below, then read on: creatinine clearance vs eGFR, the normal GFR by age, and what the CKD stages actually mean.
Creatinine Clearance (Kidney)
Estimated kidney filtration via Cockcroft-Gault.
Creatinine clearance vs eGFR: two answers to one question
Creatinine is a waste product of muscle metabolism that healthy kidneys remove at a steady rate — so the level in your blood reflects how well they filter. Two calculation families turn that level into a kidney function estimate:
- Creatinine clearance (Cockcroft-Gault) — this calculator. Estimates clearance in mL/min from age, weight, sex and serum creatinine. It is the classic formula and remains the standard reference for drug dosing, because decades of medication dosing guidance were built on it.
- eGFR (CKD-EPI) — what your laboratory prints on blood results, in mL/min/1.73 m². It is normalized to standard body size and is the modern standard for diagnosing and staging chronic kidney disease.
The two usually land close together but can diverge in very large, very small, very muscular or elderly people. When your lab report and this calculator disagree, the lab’s eGFR is the number your physicians stage disease by.
The Cockcroft-Gault equation
Published in 1976 and still in daily clinical use:
- CrCl = [(140 − age) × weight in kg] ÷ (72 × serum creatinine in mg/dL) — multiplied by 0.85 for women.
The formula captures three truths: clearance falls with age, rises with body mass, and falls as blood creatinine rises. Its known weakness is weight — in significant obesity it overestimates, which is why clinicians sometimes substitute ideal or adjusted body weight.
Normal GFR by age
Kidney function declines gradually with normal ageing — roughly 1 mL/min per year after age 40. Typical values:
| Age | Typical GFR (mL/min/1.73 m²) |
|---|---|
| 20–29 | ~116 |
| 30–39 | ~107 |
| 40–49 | ~99 |
| 50–59 | ~93 |
| 60–69 | ~85 |
| 70+ | ~75 |
An 80-year-old with a GFR of 70 may be ageing normally; a 25-year-old with the same number needs investigation. Age context is everything — which is why single cutoffs mislead.
CKD stages by GFR
Chronic kidney disease is staged by eGFR sustained for at least three months, together with markers of kidney damage such as protein in the urine:
| Stage | eGFR | Meaning |
|---|---|---|
| G1 | 90+ | Normal function (disease only if damage markers present) |
| G2 | 60–89 | Mildly decreased |
| G3a | 45–59 | Mild–moderate decrease |
| G3b | 30–44 | Moderate–severe decrease |
| G4 | 15–29 | Severe decrease — nephrology care essential |
| G5 | <15 | Kidney failure — dialysis or transplant territory |
One low reading does not diagnose CKD — dehydration, medications, recent heavy exercise and even a high-meat meal can move creatinine temporarily. Diagnosis needs a repeated pattern, which is exactly why this stays a physician’s call. Learn more on our chronic kidney disease page.
What raises creatinine besides kidney disease?
Creatinine comes from muscle, so muscular people run naturally higher levels and frail elderly people run deceptively low ones — a “normal” creatinine can hide real kidney impairment in someone with little muscle mass. Creatine supplements, dehydration, certain drugs (including common painkillers like NSAIDs) and cooked-meat-heavy meals also nudge the number. This is why formulas use age, sex and weight — and why trends matter more than single values.
Normal creatinine levels — and why “normal” needs context
Typical laboratory reference ranges: about 0.7–1.3 mg/dL for men and 0.6–1.1 mg/dL for women (roughly 60–110 µmol/L). The context that matters more than the range: creatinine tracks muscle, so a bodybuilder at 1.4 may have excellent kidneys while a frail 80-year-old at 1.0 may have significantly reduced function — the same number, opposite meanings. This is exactly why labs convert creatinine into eGFR rather than judging it raw, and why a value at the “high end of normal” in someone with little muscle mass deserves a second look, not reassurance.
The equations, honestly compared
Three generations of formulas turn creatinine into kidney function, and knowing which one produced your number avoids confusion: Cockcroft-Gault (1976, this calculator) estimates raw clearance with actual weight — still the drug-dosing reference; MDRD (1999) brought body-surface normalization but underestimated near-normal function; CKD-EPI (2009, refit 2021) fixed that bias and is today’s lab standard — the 2021 refit also removed the race coefficient after evidence it misclassified Black patients. Practical consequences: your lab report (CKD-EPI) and this calculator (Cockcroft-Gault) can legitimately differ by several points, older records may show slightly different eGFRs for identical bloodwork after the 2021 change, and none of the differences matter as much as the trend within one method.
Symptoms of declining kidney function — and why you can’t feel it
Kidneys have enormous reserve: function can halve with no symptoms at all, which is why CKD is found by blood tests, not by feel. When symptoms finally surface — typically at G4 and beyond — they are systemic and easy to misattribute: fatigue and poor concentration (uremia and anemia), swelling in legs and around the eyes, foamy urine (protein), night-time urination, itching, metallic taste and appetite loss. Two urgent exceptions can strike at any stage: sudden urine drop-off with swelling, and flank pain with fever or blood in the urine. The screening logic follows the silence: if you have diabetes, hypertension, heart disease or a family history of kidney disease, an annual eGFR plus a urine albumin check finds trouble a decade before symptoms would.
Eating for your kidneys: what evidence supports
For healthy kidneys, no special diet is needed — the kidney-protective diet is simply the cardiometabolic one: modest sodium (the blood-pressure lever), normal protein, plenty of plants, hydration, limited ultra-processed food. With established CKD, the rules genuinely change and become individual: sodium capped near 2 g/day, protein moderated (~0.8 g/kg, not high-protein plans), and — at later stages — potassium and phosphorus managed to lab values, which is renal-dietitian territory rather than internet lists, since needlessly banning potassium-rich vegetables harms more than it helps at early stages. Two universal cautions regardless of stage: regular NSAID painkillers are the most common self-inflicted kidney insult, and any supplement marketed as a “kidney cleanse” is spending your money on your risk.
Protecting your kidney function
The two biggest drivers of kidney disease worldwide are diabetes and high blood pressure — controlling both protects your GFR more than anything else. Add sensible hydration, caution with regular NSAID painkiller use, and periodic testing if you have risk factors. Acibadem’s nephrology specialists evaluate abnormal results properly, from repeat testing to imaging and treatment.
This tool is informational. A calculated clearance is an estimate for educational use — kidney disease is diagnosed and staged by a physician from laboratory results, urine studies and your history. Never adjust any medication dose yourself based on a calculator.
Frequently asked questions
What is a normal creatinine clearance?
Roughly 90–140 mL/min for men and 80–125 mL/min for women, declining naturally with age. Your lab’s eGFR report is the definitive staging number.
What is the difference between GFR and creatinine clearance?
Both estimate kidney filtration. eGFR (CKD-EPI) is normalized to body surface area and used to stage kidney disease; creatinine clearance (Cockcroft-Gault) uses your actual weight and remains the reference for drug dosing.
What level of GFR is worrying?
An eGFR persistently below 60 for three months meets the definition of chronic kidney disease and deserves nephrology input. Below 30, specialist care is essential. A single low reading should be repeated, not panicked over.
Can GFR improve?
If the cause is reversible — dehydration, a medication, an obstruction — yes, sometimes fully. Chronic damage generally does not reverse, but treating blood pressure and diabetes can slow or halt further decline for years.
Why is my creatinine high if I feel fine?
Kidney disease is silent until late stages; muscle mass, supplements or a recent gym session can also raise creatinine without disease. Repeat testing and a urine protein check separate the explanations.
Does drinking more water increase GFR?
Correcting dehydration restores your true GFR, but extra water beyond normal hydration does not push kidney function above its baseline. Hydration protects kidneys; it does not upgrade them.
Can exercise raise creatinine?
Yes — hard training in the days before a blood draw releases muscle creatinine and can nudge the result up. For a fair reading, skip intense exercise for 48 hours before testing.
What is the difference between creatinine and BUN?
Both are waste markers, but BUN (urea) also swings with hydration, protein intake and liver function, making creatinine-based eGFR the steadier kidney signal. Doctors read the pair together — a high BUN-to-creatinine ratio often just means dehydration.
Do creatine supplements damage kidneys?
In healthy people, evidence says no — but creatine raises creatinine, making kidney function look worse than it is on paper. Tell the doctor ordering your bloodwork, and pause supplementation before testing if a clean baseline matters.
How often should kidney function be checked?
With risk factors — diabetes, hypertension, heart disease, family history — annually (eGFR plus urine albumin). With diagnosed CKD, per your nephrologist’s schedule; without risk factors, routine check-ups suffice.
Numbers are a starting point — not a diagnosis
If your results raise questions, Acibadem specialists can review your situation properly: share your case and receive a free, no-obligation medical opinion from the relevant department.