eGFR Calculator
Estimated glomerular filtration rate from serum creatinine, using the 2021 CKD-EPI equation.
CKD-EPI 2021 creatinine equation, which does not include a race coefficient.
The 2021 CKD-EPI equation estimates glomerular filtration rate from serum creatinine, age, and sex. For a 60-year-old man with a creatinine of 1.0 mg/dL it gives about 86 mL/min/1.73 m², which falls in stage G2 — mildly decreased kidney function.
What eGFR measures, and why it is indexed
Glomerular filtration rate is the volume of plasma the kidneys filter each minute. Measuring it directly requires a clearance study, so in routine practice it is estimated from serum creatinine using a regression equation fitted to measured GFR in large populations. The result is reported per 1.73 m² of body surface area, a historical average, so that people of different sizes can be compared and staged on the same scale.
That indexing is the key difference from creatinine clearance. An eGFR of 55 mL/min/1.73 m² describes kidney function relative to a standard body size; a Cockcroft-Gault clearance of 55 mL/min describes this particular person’s clearance. The first is for staging chronic kidney disease, the second for adjusting drug doses.
The 2021 revision
Earlier CKD-EPI and MDRD equations included a coefficient that raised the estimate for Black patients. In 2021 a joint task force of the National Kidney Foundation and the American Society of Nephrology recommended a refitted equation without any race term, and that version is what this calculator uses. It takes creatinine, age, and sex only.
Scr is serum creatinine in mg/dL. κ = 0.7 for females and 0.9 for males; α = −0.241 for females and −0.302 for males. Divide a µmol/L result by 88.4 first. Result in mL/min/1.73 m².
Worked example: 60-year-old man, creatinine 1.0 mg/dL
The two-branch structure looks intimidating but only one branch ever does the work:
- 1 Pick the constants for the sex. For a male patient, κ = 0.9 and α = −0.302.
- 2 Divide creatinine by κ. 1.0 ÷ 0.9 = 1.111.
- 3 Take the lower branch. min(1.111, 1) = 1, and 1 raised to any power is 1 — so this term contributes nothing here.
- 4 Take the upper branch. max(1.111, 1) = 1.111, and 1.111^−1.2 = 0.881.
- 5 Apply the age term. 0.9938^60 = 0.689 — the estimate falls a little under two-thirds of a percent per year of age.
- 6 Multiply through by 142. 142 × 1 × 0.881 × 0.689 = 86.2 mL/min/1.73 m², which is stage G2.
CKD stages by eGFR
Stages G1 to G5 as used in the KDIGO classification of chronic kidney disease. Staging also requires evidence of kidney damage persisting over three months, not a single reading.
| Stage | eGFR (mL/min/1.73 m²) | Description |
|---|---|---|
| G1 | 90 or above | Normal or high |
| G2 | 60 – 89 | Mildly decreased |
| G3a | 45 – 59 | Mildly to moderately decreased |
| G3b | 30 – 44 | Moderately to severely decreased |
| G4 | 15 – 29 | Severely decreased |
| G5 | Below 15 | Kidney failure |
eGFR by age, sex, and creatinine
Calculated with the CKD-EPI 2021 equation, rounded to one decimal place.
| Age and sex | 0.8 mg/dL | 1.0 mg/dL | 1.5 mg/dL | 2.0 mg/dL |
|---|---|---|---|---|
| 30, male | 122.1 | 103.8 | 63.8 | 45.2 |
| 30, female | 101.6 | 77.7 | 47.8 | 33.8 |
| 50, male | 107.8 | 91.7 | 56.4 | 39.9 |
| 50, female | 89.7 | 68.6 | 42.2 | 29.9 |
| 70, male | 95.2 | 81.0 | 49.8 | 35.2 |
| 70, female | 79.2 | 60.6 | 37.3 | 26.4 |
What a single eGFR does not tell you
Chronic kidney disease is defined by abnormalities persisting for more than three months, so one reduced eGFR does not stage anyone — it prompts a repeat. Staging also uses albuminuria alongside eGFR, because two people at the same filtration rate can have very different risk depending on protein loss.
The estimate is least reliable where creatinine production departs from the population average: very high or very low muscle mass, limb amputation, pregnancy, and acute illness where creatinine has not yet reached a steady state. In those situations cystatin C or a measured clearance gives a better answer, and the creatinine-based estimate should be treated with caution.
This tool is an informational estimate for study and practice, not medical advice. Diagnosis and staging of kidney disease require clinical assessment by a qualified professional.