GFR Calculator
Estimate glomerular filtration rate and CKD stage using CKD-EPI and MDRD.
Inputs
Biological sex affects creatinine production. The CKD-EPI 2021 equation is race-free.
eGFR (CKD-EPI 2021)
89.8mL/min/1.73 m²
eGFR (MDRD)
77.5mL/min/1.73 m²
Tends to underestimate GFR in people with normal or near-normal kidney function.
CKD stage (per CKD-EPI)
G2
Stage description
Mildly decreased (60–89)
Creatinine (mg/dL)
1.02
Creatinine (µmol/L)
90.0
Step by step
Serum creatinine
= 1.02 mg/dL (90.0 µmol/L)
CKD-EPI 2021 (race-free)
142 × min(Scr/κ,1)^α × max(Scr/κ,1)^(−1.2) × 0.9938^Age × sex factor
= 89.8 mL/min/1.73 m²
MDRD (4-variable)
175 × Scr^(−1.154) × Age^(−0.203) × sex
= 77.5 mL/min/1.73 m²
CKD stage (CKD-EPI)
= G2 — Mildly decreased (60–89)
How it works
The GFR (glomerular filtration rate) measures how well the kidneys filter waste from the blood. eGFR is estimated from serum creatinine, age and sex. The CKD-EPI 2021 equation is the current clinical standard; it is race-free (the earlier 2009 version had a race coefficient that has been removed). MDRD is an older formula included for reference; it underestimates GFR in people with mild kidney impairment.
Formulas
CKD-EPI 2021
eGFR = 142 × min(Scr/κ,1)^α × max(Scr/κ,1)^(−1.2) × 0.9938^Age × Sf
- Scr
- Serum creatinine (mg/dL)
- κ
- 0.7 (female), 0.9 (male)
- α
- −0.241 (female), −0.302 (male)
- Sf
- 1.012 (female), 1.0 (male)
MDRD 4-variable
eGFR = 175 × Scr^(−1.154) × Age^(−0.203) × [0.742 if female]
This calculator estimates kidney function for informational and educational purposes. eGFR estimates from creatinine alone have limitations and should always be interpreted in the clinical context by a qualified healthcare provider. Do not make treatment decisions based solely on this estimate.
Frequently Asked Questions
What is a normal GFR?
A GFR ≥ 60 mL/min/1.73 m² is generally considered normal for adults (CKD stages G1–G2). Note that GFR naturally declines with age — approximately 1 mL/min/1.73 m² per year after age 30.
Why is the CKD-EPI 2021 equation race-free?
The 2009 CKD-EPI equation included a racial coefficient that produced higher eGFR estimates for Black patients, delaying referrals to nephrology. The 2021 race-free version was developed to remove this bias and is now the recommended standard in the US, UK and elsewhere.
Why do CKD-EPI and MDRD give different results?
MDRD was developed in a population with moderate to severe kidney disease and systematically underestimates GFR above 60. CKD-EPI was developed from a broader population and performs better across the full range. When both are above 60, MDRD is less reliable.
Can I use this for children?
No. CKD-EPI and MDRD are validated for adults ≥ 18 years. Paediatric kidney function is estimated with the Schwartz equation, which uses height instead of age.