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eGFR Calculator
Estimates glomerular filtration rate from serum creatinine, age and sex with the CKD-EPI 2021 race-free creatinine equation, and assigns the KDIGO GFR category (G1–G5).
When to use
You have an adult's serum creatinine (mg/dL or µmol/L), age and sex and need an eGFR in mL/min/1.73 m² or its CKD stage.
Do not use when: The person is under 18 (paediatric equations differ), creatinine is not in steady state (acute kidney injury), or you need drug-dosing clearance in mL/min (use creatinine-clearance).
Formula
eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age_years × 1.012 (if female); κ = 0.7 (female) / 0.9 (male); α = −0.241 (female) / −0.302 (male); Scr in mg/dL (µmol/L ÷ 88.4)
CKD-EPI 2021 removes the race coefficient of the 2009 equation; a CKD stage requires the eGFR to persist for more than 3 months and is less reliable at extremes of muscle mass, in pregnancy or with unstable creatinine. Results are informational only and not a substitute for clinical judgement or medical advice.
Inputs
| Parameter | Type | Unit | Required | Description |
|---|---|---|---|---|
creatinine | number | yes | Serum creatinine in the unit given by creatinine_unit. Range: > 0, ≤ 4000 | |
creatinine_unit | enum: mg_dl | umol_l | default mg_dl | Unit of the serum creatinine value (1 mg/dL = 88.4 µmol/L). | |
age_years | number | years | yes | Age in years (adults only). Range: ≥ 18, ≤ 120 |
sex | enum: male | female | yes | Sex used to select the formula coefficients or thresholds. |
Outputs
| Output | Type | Unit | Description |
|---|---|---|---|
egfr_ml_min_1_73m2 | number | mL/min/1.73 m² | Estimated GFR by CKD-EPI 2021 (creatinine), indexed to 1.73 m² body surface area. |
ckd_stage | string | G1 ≥90, G2 60–89, G3a 45–59, G3b 30–44, G4 15–29, G5 <15 mL/min/1.73 m². | |
stage_description | string | KDIGO wording for the GFR category. | |
creatinine_mg_dl | number | mg/dL | Creatinine used in the equation, in mg/dL. |
creatinine_umol_l | number | µmol/L | Same creatinine in µmol/L (× 88.4). |
Example
Female, 55 years, creatinine 1.2 mg/dL: {"creatinine":1.2,"creatinine_unit":"mg_dl","age_years":55,"sex":"female"} → {"egfr_ml_min_1_73m2":53.5,"ckd_stage":"G3a","creatinine_umol_l":106}
Male, 40 years, creatinine 0.9 mg/dL: {"creatinine":0.9,"age_years":40,"sex":"male"} → {"egfr_ml_min_1_73m2":110.7,"ckd_stage":"G1"}
Female, 70 years, creatinine 106 µmol/L: {"creatinine":106,"creatinine_unit":"umol_l","age_years":70,"sex":"female"} → {"egfr_ml_min_1_73m2":48.7,"ckd_stage":"G3a","creatinine_mg_dl":1.2}
GET https://tttkmbb.com/api/v1/calculate/egfr?creatinine=1.2&creatinine_unit=mg_dl&age_years=55&sex=female
Machine access
- API:
GET https://tttkmbb.com/api/v1/calculate/egfr(query parameters) orPOSTwith a JSON body{"inputs": {...}} - Schema: https://tttkmbb.com/api/v1/calculators/egfr · Markdown: https://tttkmbb.com/medical/egfr.md · JSON definition: https://tttkmbb.com/medical/egfr.json
- MCP: server
https://tttkmbb.com/mcp, toolrun_calculator with calculator_id="egfr" - OpenAPI operationId:
calculate_egfr - Freshness:
static. Authentication: none. Rate limit: fair use (see rate limits).
Sources
FAQ
Why does the result differ from an older lab report?
Reports before 2021–2022 often used the CKD-EPI 2009 or MDRD equations with a race coefficient; the 2021 equation gives somewhat higher values for Black adults and slightly lower values for others.
Can I use it for drug dosing?
Most dosing tables are based on Cockcroft-Gault creatinine clearance in mL/min, not BSA-indexed eGFR; use creatinine-clearance, or de-index eGFR by multiplying by BSA/1.73.
Related calculators
- Creatinine Clearance Calculator — Cockcroft-Gault clearance in mL/min for drug dosing.
- Body Surface Area Calculator — De-index eGFR to the person's actual BSA.