Softonic

eGFR Calculator

Step 1 / 4 eGFR estimate

Estimated glomerular filtration rate (eGFR) helps clinicians interpret kidney filtration from a blood creatinine result. This calculator uses the race-free 2021 CKD-EPI creatinine equation for adults and groups the result into KDIGO G categories. It is educational, not a diagnosis; CKD staging also depends on persistence, urine albumin and clinical context.

How to estimate eGFR

  1. 1

    Enter serum creatinine

    Use mg/dL. If your lab reports µmol/L, divide by 88.4 before entering the value.

  2. 2

    Enter age

    Full years. The formula is validated for adults 18 and older.

  3. 3

    Select sex

    Male or female. The equation has sex-specific coefficients.

  4. 4

    Review the G category

    Result in mL/min/1.73 m², with the CKD G1-G5 category for context.

The CKD-EPI 2021 creatinine equation

eGFR = 142 * min(Scr/kappa, 1)^alpha * max(Scr/kappa, 1)^(-1.200) * 0.9938^age * (1.012 if female)

Where Scr is serum creatinine in mg/dL, and:

  • Female: kappa = 0.7, alpha = -0.241
  • Male: kappa = 0.9, alpha = -0.302

The reporting unit is mL/min/1.73 m² of body surface area. The equation is intended for adults and laboratory creatinine values; it is an estimate, not a measured GFR.

CKD G categories

Category eGFR (mL/min/1.73 m²) Meaning
G1 ≥ 90 Normal or high; CKD requires other evidence of kidney damage
G2 60-89 Mildly decreased; CKD requires other evidence of kidney damage
G3a 45-59 Mildly to moderately decreased
G3b 30-44 Moderately to severely decreased
G4 15-29 Severely decreased
G5 < 15 Kidney failure range

CKD is classified by cause, GFR category and albuminuria category. A single eGFR, especially in G1-G2, is not enough to diagnose CKD without markers such as albuminuria, urine abnormalities, imaging findings or sustained change.

Why the 2021 equation does not use race

The older 2009 CKD-EPI creatinine equation included a coefficient for patients categorized as Black. The 2021 creatinine equation was refit without a race term so laboratories can report one equation for all adults. When comparing old and new results, check which equation the lab used because a formula change can shift the trend even when kidney function is stable.

Limitations of eGFR

  • Not reliable in acute kidney injury. The formula assumes serum creatinine is near steady state.
  • Affected by muscle mass and diet. Very high or very low muscle mass, amputation, frailty or unusual creatine intake can bias creatinine-based estimates.
  • Cystatin C can improve precision. When the result is close to an important decision point, many guidelines favor the combined creatinine-cystatin C equation if cystatin C is available.
  • Pregnancy changes kidney physiology. Do not use this equation for pregnancy.
  • Children need pediatric equations. Use a pediatric method such as Schwartz/CKiD rather than the adult CKD-EPI equation.

Interpreting a single value

A single eGFR is a snapshot. CKD diagnosis requires chronicity: reduced eGFR or markers of kidney damage for at least 3 months. Repeat unexpected or borderline results and discuss them with a clinician who can interpret trends, urine albumin and the full medical context.

Frequently Asked Questions

Some reports show an older equation alongside the 2021 CKD-EPI value, or compare current results with historical values calculated by a different method. Check the method note and compare trends using the same equation whenever possible.

This calculator expects mg/dL. Convert creatinine from µmol/L to mg/dL by dividing by 88.4, then enter the converted value.

Cystatin C is another filtration marker that is less tied to muscle mass than creatinine. The combined 2021 CKD-EPI creatinine-cystatin C equation can be more accurate in selected patients, especially when a treatment or referral decision depends on the exact category.

No. Creatinine, age and sex are used in the browser to compute the estimate. No identifiable health information is captured or stored.

Related Tools

BMI Calculator

Calculate body mass index from height and weight. Shows WHO category, healthy-weight range and limitations of BMI.

GPA Calculator

Calculate grade point average from letter grades and credit hours. Supports US 4.0 and 5.0 honors scales with the standard A/B/C/D letter table.

Inflation Calculator

Calculate the equivalent purchasing power of a dollar across any two years using historical CPI data from 1913 to today.

Scientific Calculator

Full scientific calculator with trig, log, exponents, factorial, memory, parentheses and DEG/RAD toggle. Runs in your browser.

Binomial Probability Calculator

Compute exact, cumulative and tail probabilities for a binomial distribution. Enter n trials, p success rate and k successes.

Calorie Calculator

Estimate daily calorie needs for your goal using Mifflin-St Jeor BMR and activity factors. Includes deficit and surplus targets.