Free eGFR Calculator for UK Blood Results
This eGFR calculator (often searched for as a GFR calculator) estimates how well your kidneys are filtering, using the creatinine figure from your blood test, your age and your sex. It's built for UK results, so you enter creatinine in µmol/L, the unit your lab report uses. It applies the 2021 CKD-EPI creatinine equation.
Most UK lab reports already print an eGFR next to the creatinine result. This tool is useful if yours doesn't, if you want to see how a number could change, or if you'd like to understand what the figure on your report means.
Enter your values
Estimated eGFR
The eGFR on your lab report is the one your GP will use. This estimate can differ from it by a few points.
General information only, not a diagnosis. It doesn't apply to under-18s, pregnancy, acute kidney injury, or people with very high or very low muscle mass. If your result is in mg/dL (common in the US), use our US GFR calculator instead.
How to use it
- Find creatinine on your blood test report. UK labs give it in µmol/L, usually a whole number such as 70 or 110, and typical adult results fall roughly between 45 and 120 depending on the lab, sex and muscle mass.
- Enter your age in years and select your sex.
- Select Calculate eGFR. The result is in mL/min/1.73m².
What your eGFR means
Doctors group eGFR into stages, alongside other tests such as the urine ACR:
- 90 or above (G1): normal, or CKD only if other signs of kidney damage are present
- 60–89 (G2): mildly reduced, often normal for age unless there are other signs of damage
- 45–59 (G3a): mildly to moderately reduced
- 30–44 (G3b): moderately to severely reduced
- 15–29 (G4): severely reduced
- Below 15 (G5): kidney failure range
CKD is generally diagnosed when eGFR stays below 60 for at least three months, so a single result isn't enough. Read more in our guides to CKD stages, stage 3 kidney disease and how eGFR is worked out.
Why your result may not match your lab report
- Labs can use slightly different versions of the CKD-EPI equation and round differently.
- Creatinine changes with hydration, recent intense exercise, a large cooked-meat meal, creatine supplements and illness.
- Muscle mass affects creatinine. Very muscular or very frail people can get a misleading estimate.
That's why a low result is usually repeated before anything is concluded. Our creatinine guide and urine ACR guide explain the other pieces of the picture.
When to speak to your GP
Book an appointment if your eGFR is below 60, has dropped since your last test, or you have diabetes, high blood pressure or a family history of kidney disease and haven't had your kidneys checked. If you feel very unwell, have very little urine or notice sudden swelling, contact your GP or NHS 111 promptly, or call 999 in an emergency.
Frequently asked questions
What is an eGFR calculator, and is it the same as a GFR calculator?
eGFR stands for estimated glomerular filtration rate. An eGFR calculator, often searched for as a GFR calculator, estimates how well your kidneys filter blood using your creatinine result, age and sex. It gives an estimate, not a diagnosis.
What units should I enter for creatinine?
UK laboratories report serum creatinine in micromoles per litre (µmol/L), usually a whole number such as 70 or 110. This calculator expects µmol/L. If your result is in mg/dL, which is common in the US, use our US calculator instead.
Will this match the eGFR on my blood test report?
It may be close but not identical. Laboratories can use slightly different versions of the CKD-EPI equation and round differently, so the eGFR on your report can differ by a few points. The figure on your report is the one your GP will use.
What is a normal eGFR?
An eGFR of 90 or above is usually considered normal, provided there are no other signs of kidney damage such as protein in the urine. eGFR also falls gradually with age, so readings a little below 90 in older adults are common and are not automatically a problem.
Does one low eGFR result mean I have chronic kidney disease?
No. Chronic kidney disease is generally diagnosed when eGFR stays below 60 for at least three months, or when there are other markers of kidney damage. Dehydration, illness, intense exercise and some medicines can temporarily change creatinine, so a low result is normally repeated.
Want to talk through your result?
Nisarg Ayurveda offers a free consultation to discuss complementary Ayurvedic wellness support alongside your NHS care. Bring your recent results if you have them. It doesn't replace your GP or kidney team.