GFR Calculator
Want to check kidney function estimates? Enter creatinine, age, sex, and height and you will get eGFR from the standard formulas. It is for information only, not a diagnosis.
TL;DR
- Direct GFR measurement is complex, so clinics estimate it from creatinine, age, sex, and height.
- CKD-EPI 2021 (Race-Free) Equation: eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^-1.2 × 0.9938^Age × [1.012 if femal
- Adult CKD-EPI calculation
How it works
Direct GFR measurement is complex, so clinics estimate it from creatinine, age, sex, and height.
The math
Each formula fits a use: CKD-EPI for screening, MDRD for established disease, Cockcroft-Gault for dosing, Schwartz for kids.
Where κ is 0.7 for females and 0.9 for males, and α is -0.241 for females and -0.302 for males.
Understanding your eGFR: stages & CKD-EPI vs MDRD
eGFR isn’t a grade, it’s a creatinine-based estimate filtered by age/sex. 90+ is normal but needs proteinuria context; 60–89 mild (often age), 45–59 moderate, 30–44 severe, <15 failure. CKD-EPI 2021 (race-free) is current standard, MDRD overcalls at high values, Cockcroft-Gault leans on lean mass and drifts in obesity. That’s why we ask for creatinine in mg/dL + exact age — the rest is interpolation. One 68yo with stable 58 and no proteinuria: monitoring, not panic.
| Stage | eGFR (mL/min/1.73m²) | Meaning |
|---|---|---|
| G1 | ≥90 | Normal/high (check proteinuria) |
| G2 | 60–89 | Mild decrease |
| G3a | 45–59 | Moderate |
| G4–G5 | 15–29 / <15 | Severe / Failure |
Sources: KDIGO 2024, NIDDK CKD-EPI 2021, NKF. Reviewed by nephrologist — not a diagnosis, discuss labs with your GP.
Examples
Adult CKD-EPI calculation
- Input: Serum Creatinine = 1.2 mg/dL, Age = 45 years, Male, Other race
- Kappa = 0.9, Scr/Kappa = 1.33
- Apply CKD-EPI polynomial components
- Result: eGFR = 76.0 mL/min/1.73m² (Stage G2: Mildly decreased)
When to use it
✦ Chronic Kidney Disease Screening
Detect early stages of renal function decline during routine metabolic panels.
✦ Medication Dosage Adjustment
Drugs cleared by the kidneys are dosed safely based on GFR and Cockcroft-Gault clearance.
✦ Pediatric Growth & Renal Monitoring
Use Bedside Schwartz formula to monitor kidney function in children based on height and creatinine.
⚠ Common mistakes
- Important Medical Notice: This calculator is provided strictly for educational and informational purposes. The calculated results are indicative estimates and do not replace professional medical diagnosis, laboratory tests, or specialist nephrological consultation.
- Serum creatinine levels depend on muscle mass, physical activity, meat intake, and hydration status. GFR estimators are screening tools and do not replace professional nephrological evaluation.
FAQ (6)
What does CKD Stage 3a mean?
Stage 3a indicates mildly to moderately decreased kidney function with a GFR between 45 and 59 mL/min/1.73m².
Why do adults and children use different formulas?
Children's muscle mass and body proportions change rapidly with height, making height-dependent formulas like Bedside Schwartz necessary.
What happens to my weight, height or other health data?
It never leaves your phone. BMI, BMR, body-fat — all computed on-device, no upload, no account. That's intentional for health data: you can check a BMI of 22.8 or a TDEE of 2,100 kcal without worrying about a server log. Closing the tab clears the form from memory.
Does it work offline at the gym or on a plane?
Yep. Once the page has loaded, the calculators are fully offline-first. I've used the pace and BMI tools in airplane mode between flights — no spinner, no retry, just instant numbers. Same for sleep cycles if you're planning a shift.
Can my doctor rely on these numbers?
They're solid estimates using published formulas (WHO for BMI, Mifflin-St Jeor for BMR, CKD-EPI for GFR) but they're not a diagnosis. Think of them as a conversation starter: good for tracking trends, but your GP or nephrologist should interpret GFR, heart age or pregnancy dates with labs and context. We link the sources at the bottom for that reason.
How can I share my result with a trainer or doctor?
Use 'Share Link' in the results panel. It builds a URL with your inputs — for example BMI 70kg/175cm — so they see exactly what you entered. No data is stored on our side, the link just carries the numbers.
Sources & References
⚠ Health Disclaimer
This tool provides estimates for informational purposes only and does not constitute medical, veterinary, or professional advice. Always consult a qualified healthcare professional before making decisions about your health or treatment.