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Blood Test Tracker

eGFR calculator (CKD-EPI 2021, creatinine)

An estimate of how well your kidneys filter blood, worked out from your creatinine, age and sex. Type your results in the units on your report and it works out eGFR as you type, in your browser.

AI-verified against cited sources. Awaiting expert reviewLast reviewed 2026-10-03Kidneys

In years, on the day of the blood test.
years
The equation has a version for each.

Type your results above, or fill in the example, to see eGFR.

Nothing you type here leaves your browser.

Educational information, not medical advice. Blood Test Tracker doesn’t diagnose or treat, and it doesn’t replace your clinician. Talk with your clinician before changing medications, supplements or care.

How it’s worked out

The formula

eGFR (mL/min/1.73 m²) = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age × 1.012 [if female]; Scr = serum creatinine in mg/dL, age in years; κ = 0.7 (female) or 0.9 (male); α = −0.241 (female) or −0.302 (male)

When the equation works

Outside these limits the calculator says so instead of giving a number.

  • Creatinine: 0.2 to 15 mg/dL
  • Age: 18 years and over

A worked example

Example numbers, not anyone’s real results, run through the same code as the calculator above.

Example inputs and the result
Creatinine1 mg/dL
Age60 years
SexFemale
eGFR64 mL/min/1.73 m²

For a woman aged 60, this result is in the usual range.

What eGFR tells you

eGFR stands for estimated glomerular filtration rate. Your kidneys filter waste out of your blood, and GFR is how much blood they filter each minute. A routine test can't measure that directly. So the lab estimates it from your blood creatinine level, your age and your sex. Many labs now use the 2021 CKD-EPI equation, which does not use race.

eGFR is the main number clinicians use to describe kidney function. An eGFR below 60 that lasts 3 months or more is one of the standard criteria for chronic kidney disease. Early kidney disease often causes no symptoms, so this number is often how it is first noticed. eGFR is read together with a urine albumin test (uACR), because kidney damage can show up in either one.

Read the full page on eGFR, with what a high or low result can mean.

Usual ranges

The ranges the result above is placed on. Your own lab’s printed range comes first if it gives one.

Sources

The equation

  1. CKD-EPI Creatinine Equation (2021), National Kidney Foundation
  2. New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race, New England Journal of Medicine (2021)
  3. Estimated Glomerular Filtration Rate Calculators, NIDDK
5 more sources for the ranges and the explanation
  1. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease, Kidney International 105(4S):S117-S314 (2024)
  2. Estimated Glomerular Filtration Rate (eGFR), National Kidney Foundation
  3. Creatinine With eGFR (test 3005478), ARUP Laboratories
  4. CRTS1 - Creatinine with Estimated Glomerular Filtration Rate (eGFR), Serum, Mayo Clinic Laboratories
  5. eGFR (CKD-EPI) - výpočet, Laboratorní příručka Centrální laboratoře NNB, Nemocnice Na Bulovce, Prague (2021)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. The calculator is version 1.0.0 of our code for this equation, tested against published examples. How we build and check these pages.

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