GFR Calculator guide
GFR Calculator: Estimate Your Kidney Function (eGFR)
Use our GFR calculator to estimate kidney function (eGFR) from serum creatinine in µmol/L or mg/dL with the CKD-EPI equation, and see your CKD category.
By the AllCalculator editorial teamUpdated 16 October 20262 min read
Your estimated glomerular filtration rate (eGFR) shows how well your kidneys are filtering waste from your blood. It's worked out from a blood test for creatinine, and it's the main test used to check for chronic kidney disease (CKD). Our GFR Calculator estimates it the same way labs do.
How to use the calculator (GFR Calculator)
- Choose your sex and enter your age.
- Enter your serum creatinine from your blood test, in µmol/L (UK labs) or mg/dL.
- Choose the equation.
You'll see your eGFR and its category from G1 to G5.
The equations
Both use the CKD-EPI creatinine equation:
- CKD-EPI 2009, without the ethnicity adjustment: recommended by NICE and used by most UK labs.
- CKD-EPI 2021: a race-free refit of the equation, recommended in the United States.
The 2021 version usually gives a slightly higher result. To convert creatinine, 1 mg/dL = 88.4 µmol/L.
eGFR categories
| Category | eGFR | Kidney function |
|---|---|---|
| G1 | 90 or more | Normal or high |
| G2 | 60 to 89 | Mildly decreased |
| G3a | 45 to 59 | Mildly to moderately decreased |
| G3b | 30 to 44 | Moderately to severely decreased |
| G4 | 15 to 29 | Severely decreased |
| G5 | Below 15 | Kidney failure |
A worked example
With the calculator's default settings, a 55-year-old woman with a creatinine of 80 µmol/L has an eGFR of about 72 using the 2009 equation. That's category G2.
Frequently asked questions
Does an eGFR of 60 to 89 mean I have kidney disease?
Not on its own. eGFR naturally falls with age. CKD is only diagnosed with an eGFR under 60, or with other signs of kidney damage such as protein in your urine, for at least 3 months.
Why did my result change?
Creatinine can be affected by eating meat, hard exercise, dehydration, pregnancy and some medicines. That's why a low result is usually repeated.
Can I use this to adjust my medicines?
No. Always speak to your GP or pharmacist. Some medicine doses use a different measure, creatinine clearance.
For a medicine dosing calculation for nurses and students, see our Nursing Dosage Calculator.
Sources and further reading
- NICE: Chronic kidney disease – assessment and management (NG203)nice.org.uk
- NHS: Chronic kidney disease – diagnosisnhs.uk
- National Kidney Foundation: CKD-EPI creatinine equation (2021)kidney.org
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This guide is general information to help you understand your options. It isn't financial, tax, legal or building advice and doesn't take your personal circumstances into account. Figures were checked when the guide was last updated and can change, so confirm anything important with GOV.UK, HMRC, a regulated adviser or a qualified tradesperson.