eGFR Calculator
Estimate your kidney function (eGFR) from a serum creatinine result using the CKD-EPI (2009) creatinine equation without the ethnicity coefficient — the equation recommended by NICE (NG203) for UK clinical practice — and see the corresponding eGFR category band.
Where Your Result Sits on the eGFR Category Scale
eGFR Category Reference (KDIGO Banding)
eGFR Calculator: Estimate Your Kidney Function
Our eGFR Calculator estimates your kidney function from a serum creatinine result using the CKD-EPI (2009) creatinine equation, applied without the ethnicity coefficient in line with NICE guidance (NG203) for UK clinical practice. Enter your creatinine result, age and sex to see your estimated glomerular filtration rate and where it sits on the eGFR category scale.
What Is eGFR?
eGFR stands for estimated Glomerular Filtration Rate. It’s a measure of how well your kidneys are filtering waste from your blood, expressed in millilitres per minute per 1.73m² of body surface area (mL/min/1.73m²). Most UK laboratories calculate and report eGFR automatically alongside a routine blood test, using the same creatinine result this calculator uses.
How to Use This Calculator
- Enter your serum creatinine result – found on your blood test report, usually in micromol/L (µmol/L) on UK reports.
- Select the correct unit – most UK labs report in µmol/L; some international reports use mg/dL.
- Enter your age – this equation is validated for adults aged 18 and over.
- Select your sex – the equation uses sex-specific coefficients.
- Click Calculate eGFR to see your estimated result and eGFR category.
The CKD-EPI (2009) Equation, Without the Ethnicity Coefficient
This calculator uses the CKD-EPI (2009) creatinine equation, applied without the ethnicity coefficient that formed part of the original 2009 publication. NICE guidance (NG203) recommends UK laboratories use CKD-EPI without this correction factor. NICE guidance also notes that the newer CKD-EPI (2021) race-free equation has not been validated in UK populations, so this calculator does not use it.
| Parameter | Female | Male |
|---|---|---|
| κ (kappa) | 0.7 | 0.9 |
| α (alpha) | -0.329 | -0.411 |
| Sex multiplier | × 1.018 | × 1.000 |
An age decay factor of 0.993 per year is applied to both sexes. Serum creatinine is converted to mg/dL for the calculation (1 mg/dL = 88.4 µmol/L). The ethnicity coefficient historically included in the 2009 publication is not applied, in line with NICE guidance.
Understanding CKD Stages
Chronic Kidney Disease (CKD) stages are banded by eGFR result, using the KDIGO (Kidney Disease: Improving Global Outcomes) classification also referenced in NICE guidance:
| Stage | eGFR Range (mL/min/1.73m²) | Description |
|---|---|---|
| G1 | 90 or above | Normal or high |
| G2 | 60 – 89 | Mildly decreased |
| G3a | 45 – 59 | Mild-moderate decrease |
| G3b | 30 – 44 | Moderate-severe decrease |
| G4 | 15 – 29 | Severely decreased |
| G5 | Below 15 | Kidney failure |
A single eGFR reading, on its own, does not diagnose CKD. NICE guidance (NG203) describes CKD as abnormalities of kidney structure or function that are present for more than three months. A CKD diagnosis is normally confirmed by a repeat eGFR test at least 90 days apart and/or other evidence of kidney damage, most commonly a raised urine albumin:creatinine ratio (ACR).
Factors That Can Affect Your eGFR Result
- Muscle mass: Creatinine is a byproduct of muscle metabolism, so very high or very low muscle mass (bodybuilders, amputees, people with muscle-wasting conditions) can make creatinine-based eGFR less accurate.
- Recent illness or dehydration: An acute illness, dehydration, or recent intense exercise can temporarily raise creatinine and lower the calculated eGFR.
- Diet: A very high-protein diet, particularly a large intake of cooked meat shortly before the test, can raise creatinine slightly.
- Certain medications: Some medicines can affect creatinine levels or genuinely affect kidney function – your GP can advise if this applies to you.
- Pregnancy: This equation is not validated for use during pregnancy.
Frequently Asked Questions
Is a low eGFR always a sign of kidney disease?
Not necessarily. A single low reading can be caused by dehydration, recent illness, certain medications, or high protein intake before the test. NICE guidance generally requires reduced kidney function to be present for three months or more, confirmed by a repeat test, and/or other evidence of kidney damage such as a raised urine ACR, before a CKD diagnosis is made. Always discuss an unexpected result with your GP rather than relying on a single reading.
What is a normal eGFR result?
An eGFR of 90 or above is generally considered normal, though it naturally declines somewhat with age. A result between 60 and 89 is common in older adults and does not, on its own, indicate CKD unless it persists over time or other evidence of kidney damage, such as protein in the urine, is also present.
Why doesn’t this calculator use an ethnicity coefficient?
The original 2009 CKD-EPI equation included a coefficient that adjusted results for patients identified as Black, based on population-level creatinine data. NICE guidance (NG203) recommends UK laboratories use the CKD-EPI equation without this correction factor. A newer, formally recalibrated CKD-EPI (2021) equation that also omits an ethnicity term exists, but NICE notes it has not been validated in UK populations, so this calculator uses the NICE-recommended CKD-EPI (2009) equation without the ethnicity coefficient instead.
What’s the difference between eGFR and creatinine clearance?
eGFR (this calculator) is derived from a formula using serum creatinine, age and sex, and is the routine screening measure reported with most blood tests. Creatinine clearance, often estimated using the Cockcroft-Gault formula, additionally factors in body weight and is sometimes preferred for drug dosing decisions. Our Creatinine Clearance Calculator covers this alternative method.
Can I use this calculator if I’m under 18 or pregnant?
No. The CKD-EPI (2009) equation used here is validated for adults aged 18 and over and is not intended for use during pregnancy. Kidney function in children is assessed using different, age-specific formulas, and a GP or paediatric specialist should be consulted directly.
What should I do if my eGFR result is low?
Book an appointment with your GP to discuss the result in context – alongside your medical history, any medications, and a urine test if needed. Do not attempt to interpret an unexpected or low eGFR result on your own, and do not delay seeking medical advice based on this or any online calculator.