MDRD eGFR Calculator
Use this tool to estimate kidney function using the 4-variable MDRD equation (mL/min/1.73 m²).
What is GFR and why it matters
Glomerular filtration rate (GFR) is one of the most useful markers for kidney function. It estimates how much blood your kidneys filter each minute, standardized to a body surface area of 1.73 m². In clinical practice, GFR helps with chronic kidney disease (CKD) staging, medication dosing decisions, and long-term monitoring.
Because direct GFR measurement is complex, clinicians usually rely on equations that estimate GFR from routine lab data. The MDRD formula is one of the classic methods for estimating kidney function in adults.
How the MDRD calculator works
This page uses the 4-variable MDRD equation:
eGFR = 175 × (Scr)-1.154 × (Age)-0.203 × (0.742 if female) × (1.212 if Black)
- Scr = serum creatinine in mg/dL
- Age = age in years
- Female factor = multiplies result by 0.742
- Legacy Black coefficient = multiplies result by 1.212 if applied
If you enter creatinine in µmol/L, the calculator automatically converts it to mg/dL using 88.4 µmol/L = 1 mg/dL.
How to interpret your eGFR result
eGFR is interpreted in context. A single value is helpful, but trends over time are more meaningful than one isolated measurement.
| eGFR (mL/min/1.73 m²) | CKD Category | General Interpretation |
|---|---|---|
| ≥ 90 | G1 | Normal/high (if other signs of kidney disease are present) |
| 60–89 | G2 | Mildly decreased |
| 45–59 | G3a | Mild to moderate decrease |
| 30–44 | G3b | Moderate to severe decrease |
| 15–29 | G4 | Severely decreased |
| < 15 | G5 | Kidney failure range |
Important clinical context
- CKD diagnosis requires persistence (typically at least 3 months) and/or other markers such as albuminuria.
- Acute changes in creatinine can make estimated formulas less reliable.
- Medication doses may use different kidney function methods depending on drug labeling.
MDRD vs CKD-EPI
MDRD has been historically important, but many health systems now prefer CKD-EPI equations because they often provide better accuracy, especially at higher GFR levels. In addition, newer CKD-EPI models avoid race-based adjustment. Still, MDRD remains common in older datasets, publications, and legacy calculators.
When MDRD may be less accurate
- Pregnancy
- Children and adolescents
- Very low or very high muscle mass
- Rapidly changing kidney function (acute kidney injury)
- Extremes of diet or unusual creatinine generation
Practical tips for kidney health
- Control blood pressure and blood sugar if you have hypertension or diabetes.
- Limit excess sodium and ultra-processed foods.
- Stay physically active and maintain a healthy weight.
- Avoid unnecessary NSAID use unless advised by your clinician.
- Review over-the-counter supplements with a healthcare professional.
- Monitor kidney labs regularly if you are at risk.
Frequently asked questions
Is a low eGFR always permanent?
Not always. Some causes are temporary, especially if related to dehydration, medication effects, or acute illness. Persistent reduction over time is more concerning for CKD.
Can I use this calculator for diagnosis?
This tool is educational and useful for quick estimation, but it does not replace medical diagnosis. Clinical decisions should include lab trends, urine studies, symptoms, and professional evaluation.
Why include a race coefficient option?
The classic MDRD equation included this factor. Because many institutions now use race-neutral approaches, this calculator labels the option as legacy and leaves it user-selectable.
Medical disclaimer: This calculator provides an estimate only and is not a substitute for professional medical care. If your result is unexpectedly low or you have symptoms (swelling, fatigue, reduced urine output, shortness of breath), contact a qualified healthcare professional promptly.