eGFR Calculator NHS
This independent UK eGFR calculator estimates kidney filtration using the CKD-EPI 2009 creatinine equation without an ethnicity adjustment, in line with current NICE and UK Kidney Association guidance for adults.
eGFR calculator
What is eGFR?
Estimated glomerular filtration rate (eGFR) is an estimate of how well the kidneys filter blood. UK laboratories routinely report eGFR alongside serum creatinine. The estimate uses creatinine, age and sex.
How to use this calculator
- Enter your age. This calculator is for adults aged 18 or over.
- Select the sex variable used by the CKD-EPI equation.
- Enter serum creatinine in µmol/L from a blood test.
- Select Calculate to see the estimated GFR and G category.
Formula and methodology
This calculator uses the CKD-EPI 2009 creatinine equation without an ethnicity adjustment. Creatinine entered in µmol/L is converted to mg/dL by dividing by 88.4 before the equation is applied. Current NICE guidance recommends CKD-EPI for creatinine-based eGFR without an ethnicity adjustment; the UK Kidney Association advises that CKD-EPI 2021 should not currently be used in UK practice because it has not been validated in UK populations.
eGFR categories
| Category | eGFR (mL/min/1.73 m²) |
|---|---|
| G1 | 90 or above |
| G2 | 60–89 |
| G3a | 45–59 |
| G3b | 30–44 |
| G4 | 15–29 |
| G5 | Below 15 |
G1 and G2 categories do not by themselves mean that a person has CKD. Kidney disease assessment also considers markers such as urine albumin-to-creatinine ratio (ACR), structural abnormalities and whether abnormalities persist over time.
Worked example
For a 60-year-old male with serum creatinine of 100 µmol/L, the calculator converts creatinine to about 1.13 mg/dL and applies CKD-EPI 2009. The result is an estimate rather than a direct measurement of GFR.
Important limitations
eGFR assumes creatinine is stable, so it is not valid when creatinine is changing rapidly, such as during acute kidney injury. The CKD-EPI adult equation is not validated for people under 18 or during pregnancy. Estimates may also be less reliable at extremes of muscle mass or body habitus, including severe malnutrition, bodybuilding, amputation, oedema or severe obesity. Trends over time can be more informative than a single result.
eGFR and creatinine clearance are not interchangeable. Some medicines, including situations highlighted by the MHRA such as direct-acting oral anticoagulants and certain narrow-therapeutic-index medicines, may require creatinine clearance rather than eGFR for dose decisions.
Authoritative sources
- NICE NG203: Chronic kidney disease assessment and management
- UK Kidney Association: Measurement of kidney function
Related calculators
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FAQs
What formula does this UK eGFR calculator use?
It uses the CKD-EPI 2009 creatinine equation without an ethnicity adjustment.
Is an eGFR of 60 to 89 chronic kidney disease?
Not necessarily. In the absence of other evidence of CKD, an eGFR of 60 to 89 may be classified as normal. CKD assessment also considers other markers and persistence over time.
Can this calculator be used during pregnancy?
No. The CKD-EPI equation is not validated for pregnancy.
Can I use eGFR to adjust every medicine dose?
No. eGFR and creatinine clearance are different estimates, and some medicines require creatinine clearance or specialist guidance for dosing.
Medical disclaimer: This independent calculator is for general information only. It is not an NHS diagnostic service and must not replace laboratory reporting, clinical assessment or advice from a qualified healthcare professional.