Serum Creatinine (mg/dL) Enter your serum creatinine level from a blood test (e.g., 1.0)

Age (years) Enter your age in whole years (18-120)

Sex Select your sex Male Female Select male or female for accurate calculation

Quick Examples:

Healthy Adult Male Female with Elevated Creatinine

Calculate Clear

This calculator is a screening tool only, not a diagnostic instrument. It is not intended to replace professional medical evaluation. Consult a healthcare provider.

What Is Estimated Glomerular Filtration Rate

Estimated glomerular filtration rate, or eGFR, is a number that shows how well your kidneys are filtering waste from your blood. Your kidneys have tiny filters called glomeruli that clean your blood every minute. A higher eGFR means your kidneys are working better. A lower number may suggest that your kidneys are not filtering as well as they should. Doctors use this number to check kidney health over time.

How Estimated Glomerular Filtration Rate Is Calculated

Formula

This formula starts by comparing your creatinine level to a reference value based on your sex. If your creatinine is below that reference, one part of the formula applies. If it is above, another part applies. Then the formula adjusts for your age because kidney function naturally changes as we get older. For women, a small adjustment factor is added. The result gives an estimate of how much blood your kidneys filter each minute, standardized to a typical body size.

Why Estimated Glomerular Filtration Rate Matters

Knowing your eGFR helps you and your doctor understand how well your kidneys are working. This number can catch kidney problems early, often before you feel any symptoms. Early awareness may help you make choices that support kidney health.

Why Kidney Function Is Important for Overall Health

When kidney function declines, waste products can build up in the blood. This may lead to health issues that affect the heart, bones, and other organs. Kidney problems often develop slowly without obvious warning signs. Regular monitoring may help identify changes early, when there may be more options for supporting kidney health. Ignoring kidney function numbers could mean missing the chance to address problems before they become more serious.

For Different Age Groups

eGFR naturally tends to decrease as people get older. What is considered a typical eGFR for a 30-year-old may differ from what is typical for an 80-year-old. Older adults may have somewhat lower eGFR values without necessarily having kidney disease. Doctors consider age when interpreting eGFR results and may use different expectations for different age groups.

eGFR vs Serum Creatinine

Serum creatinine is a waste product measured directly in a blood test. eGFR is calculated from that creatinine level along with your age and sex. A higher creatinine level usually means a lower eGFR. Some people focus only on creatinine, but eGFR is often easier to understand because it accounts for personal factors and gives a clearer picture of kidney function. Both numbers are useful, but they tell you different things about your kidney health.

Example Calculation

Consider a 40-year-old man who recently had a blood test. His serum creatinine level is 1.0 mg/dL. He wants to understand his kidney function. He enters his creatinine of 1.0 mg/dL, age of 40 years, and selects male into the calculator.

The calculator uses κ = 0.9 for a male, so the ratio is 1.0 divided by 0.9, which equals 1.11. Since this is greater than 1, the min function gives 1 and the max function gives 1.11. The formula then calculates: 142 × 1^(-0.302) × 1.11^(-1.200) × 0.9938^40. This results in an eGFR of approximately 98 mL/min/1.73 m².

Result: eGFR = 98 mL/min/1.73 m², CKD Stage G1 (Normal kidney function)

An eGFR of 98 falls within the normal range, which is 90 or higher. This suggests his kidneys are filtering blood well. He may consider maintaining his current lifestyle and discussing this result with his doctor at his next check-up. Regular testing over time can help track any changes in kidney function.

Frequently Asked Questions

Who is this GFR Calculator for?

This calculator is designed for adults age 18 and older who want to estimate their kidney function. It may be useful for people who have had a recent blood test showing serum creatinine levels. Healthcare providers may also use it as a quick reference tool during patient discussions.

How often should I check my eGFR?

The frequency of eGFR testing depends on your health situation. People with diabetes, high blood pressure, or a family history of kidney disease may need more frequent testing. Your healthcare provider can recommend how often you should have your kidney function checked based on your personal health factors.

Can children use this calculator?

No, this calculator is not designed for children under 18. The CKD-EPI formula used here is validated for adults only. Children have different normal creatinine levels and kidney function patterns. A pediatric healthcare provider can use age-appropriate formulas for children.

Can I use this calculator if I have only one kidney?

This calculator uses a standard formula for the general population and may not account for your specific situation. People with one kidney may have different expected eGFR values. It is recommended to discuss your kidney function results with a healthcare provider who understands your medical history.

What factors can affect my creatinine level besides kidney function?

Creatinine levels can be influenced by muscle mass, diet, certain medications, and exercise. People with higher muscle mass may have naturally higher creatinine levels. Very low muscle mass or certain diets may lead to lower creatinine. These factors may affect how well the eGFR formula estimates kidney function for some individuals.