Estimate your Glomerular Filtration Rate (eGFR) — the best overall measure of kidney function — using the CKD-EPI 2021, MDRD, and Cockcroft-Gault equations.
Normal creatinine: 0.7–1.2 mg/dL. Values from a standard blood test (CMP or BMP).
| Equation | Best Used For |
|---|---|
| CKD-EPI 2021 | Current standard; race-free; most accurate for adults |
| MDRD | Historical standard; less accurate at higher GFR |
| Cockcroft-Gault | Drug dosing; estimates creatinine clearance (CrCl) |
| Stage | eGFR | Description |
|---|---|---|
| G1 | ≥ 90 | 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 | 0–14 | Kidney Failure |
Important: This calculator is for informational purposes only. eGFR should be interpreted by a healthcare professional alongside other clinical information. A single eGFR value does not diagnose CKD — diagnosis requires persistently low eGFR for ≥ 3 months.
A creatinine of 1.0 mg/dL is not a universal pass mark. It looks tidy because it sits inside the reference range the page prints for both sexes, yet the same 1.0 gives an eGFR of 94.6 for a 45-year-old man and 58.8 for a 75-year-old woman, which fall in different CKD categories. This calculator turns creatinine, age and sex into three estimates, with the 2021 CKD-EPI equation as the headline number, and shows where it sits in the KDIGO G1 to G5 bands.
CKD-EPI 2021 is the race-free creatinine equation from the NKF-ASN task force (Inker and colleagues, New England Journal of Medicine, 2021): eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age, multiplied by 1.012 for women. Scr is serum creatinine in mg/dL, κ is 0.7 for women and 0.9 for men, and α is −0.241 for women and −0.302 for men. The result is in mL/min/1.73 m². If you pick μmol/L, the page divides by 88.42 to get mg/dL first.
The page also reports MDRD, 175 × Scr^−1.154 × age^−0.203 (× 0.742 for women, with the original race coefficient left out), and Cockcroft-Gault, CrCl = (140 − age) × weight in kg ÷ (72 × Scr), × 0.85 for women. Cockcroft-Gault is in plain mL/min, not scaled to body surface area, and uses the actual weight you type.
What changes if one input moves. Hold a 45-year-old man at 1.0 mg/dL and CKD-EPI gives 94.6. Creatinine of 0.8 gives 111.2, 1.2 gives 76.0, 1.5 gives 58.1 and 2.0 gives 41.2, so a rise from 1.0 to 1.5 cuts the estimate by about 39 percent. Age acts more gently: at creatinine 1.0 the same man scores 107.1 at 25, 94.6 at 45, 83.5 at 65 and 73.8 at 85. Weight has no effect on CKD-EPI or MDRD and enters only the Cockcroft-Gault figure.
Worked example: a 62-year-old woman, creatinine 1.1 mg/dL, 68 kg. Scr/κ = 1.1 ÷ 0.7 = 1.571, so the min term is 1 and the max term is 1.571^−1.2 = 0.581. The age factor is 0.9938^62 = 0.680. eGFR = 142 × 0.581 × 0.680 × 1.012 = 56.8 after rounding to one decimal, which the page labels G3a. MDRD gives 50.3. Cockcroft-Gault is (140 − 62) × 68 ÷ (72 × 1.1) = 67.0, times 0.85 = 56.9 mL/min.
Labs may use a different equation, different rounding, or a cystatin C based estimate, so a gap of several points is normal. The lab's reported value is the one your clinician is working from.
No. KDIGO guidance defines CKD as kidney abnormalities lasting more than three months, and staging also looks at albumin in the urine. A single reading can dip with dehydration, acute illness or certain medicines. The short text under the banner is general, and the stronger lines for G4 and G5 deserve a clinician's interpretation rather than a conclusion drawn from one estimate.
Creatinine comes from muscle. Large muscle mass or creatine supplements can raise serum creatinine without any kidney problem, so eGFR reads low, while very low muscle mass can make kidneys look better than they are. Cystatin C testing is the usual cross-check, which NIDDK also mentions among kidney function tests.
CKD-EPI 2021 drives the staging banner and is the equation current guidelines favor for adults. MDRD is older and tends to read low at higher filtration rates. Cockcroft-Gault estimates creatinine clearance, is mostly used for drug-dose labeling, and moves with the weight you enter.
No. These equations assume stable kidney function in adults. They are not meant for acute kidney injury, pregnancy, dialysis or children, who have their own equations. This page is educational and cannot replace a doctor's assessment.
Typing 1.0 while μmol/L is selected is treated as about 0.011 mg/dL and returns an eGFR near 400, which should be a clue. Check that the unit selector matches your lab sheet.