eGFR (Estimated Glomerular Filtration Rate) estimates how effectively the kidneys filter waste products from the blood. It is calculated using serum creatinine, age, and sex.

Can eGFR be inaccurate?

Yes. eGFR may be less accurate in people with very high muscle mass, frailty, pregnancy, severe illness, amputations, or unusual body composition. Always interpret results with your doctor.

Is a low eGFR always kidney disease?

Not always. Chronic kidney disease (CKD) is usually diagnosed only when reduced eGFR persists for at least 3 months or when other markers of kidney damage are present. A single low result should be discussed with your doctor.

eGFR Calculator (CKD-EPI 2021) – Estimate Kidney Function Using Creatinine

Q: Why does age affect eGFR?

Kidney filtration naturally declines slightly with age, so age is included in the CKD-EPI equation to produce a more accurate estimate.

Q: Why are there two creatinine units?

Some laboratories report creatinine in mg/dL while others use µmol/L (micromol/L). These are different units for the same measurement. Always select the correct unit when using this calculator, as the wrong choice will produce an incorrect eGFR.

🫘 What is this tool?

This tool estimates your eGFR (Estimated Glomerular Filtration Rate) — a number that shows how well your kidneys are filtering your blood. You will need three things from your laboratory report:

Your serum creatinine value (a number from your blood test)
Your age in years
Your sex (male or female)

For adults aged 18 and above only. Uses the CKD-EPI 2021 creatinine equation.

Age & Sex Creatinine Result

Your age and sex

Enter your age in years and select your biological sex as recorded in your medical records.

ℹ️ This calculator is for adults aged 18 and above only. It is not designed for children — their kidney function is calculated differently.

Age (in completed years)

This calculator is for adults aged 18 and above only. For children, please use a paediatric kidney function calculator for accurate results.

Biological sex

Your creatinine value

Find the Serum Creatinine result on your laboratory report. Enter the number exactly as shown.

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Important — select the correct unit!
Creatinine is reported in two different units depending on the laboratory:
• mg/dL — example: 0.9 mg/dL or 1.2 mg/dL
• µmol/L (micromol/L) — example: 80 µmol/L or 110 µmol/L
Selecting the wrong unit will produce a completely incorrect result. Always check your report carefully before choosing.

Serum Creatinine value

Type in only the number — do not include the unit text.

Please enter a valid creatinine value greater than 0.

Unit of creatinine (from your report)

Please select the unit from your laboratory report.

Your eGFR Result

Details You Entered

Your Estimated GFR

—

mL/min/1.73m²

Calculated using the CKD-EPI 2021 Creatinine Equation

⚠️ Please note: This is an estimated value only. eGFR alone is not enough to draw any conclusions about kidney health — there are many reasons a value may be low or high, and interpretation requires your full medical history, other test results, and clinical assessment. Always discuss this result with your doctor.

Understanding Your eGFR Result

eGFR (Estimated Glomerular Filtration Rate) is one of the most important kidney function tests. It estimates how many millilitres of blood your kidneys filter per minute, adjusted for body surface area. The higher the number, the better the kidney function.

eGFR Interpretation Categories (CKD Staging)

eGFR (mL/min/1.73m²)	Category	What it means
90 or above	Normal or High	Kidneys are working well. May still have kidney damage if other findings are present.
60 – 89	Mildly Reduced	Slight reduction in kidney filtering. Often no symptoms. Monitor regularly.
45 – 59	Mild to Moderate Reduction	Moderate reduction. Requires medical review and monitoring.
30 – 44	Moderate to Severe Reduction	Significant reduction. Medical management is important.
15 – 29	Severely Reduced	Severe reduction in kidney function. Specialist review is essential.
Below 15	Kidney Failure Range	Very low kidney function. Requires urgent specialist care. May need dialysis.

What is the CKD-EPI 2021 Equation?

This calculator uses the CKD-EPI 2021 Creatinine Equation, which is one of the most widely used modern formulas for estimating kidney function in adults. It was developed to be more accurate than older equations, especially for people with mildly reduced kidney function.

The formula uses your serum creatinine level, age, and sex. It does not use race as a variable (the 2021 update removed the race coefficient to make the equation more universally applicable).

Why Are There Two Creatinine Units?

Different countries and laboratories use different measurement units for creatinine. Sri Lankan laboratories commonly report creatinine in µmol/L (micromol per litre). Some international reports and older reports may use mg/dL (milligrams per decilitre). The values represent the same thing but on a different scale — 1 mg/dL is approximately equal to 88.4 µmol/L. Always check which unit your report uses before entering the value.

When eGFR May Be Less Accurate

The CKD-EPI equation may give less reliable estimates in:

• Very muscular individuals (bodybuilders, athletes) — creatinine may be higher than average, making eGFR appear falsely low
• Frail or elderly patients — less muscle mass can make eGFR appear falsely high
• Pregnancy — special reference ranges apply
• Severe acute illness — creatinine changes rapidly and does not reflect true long-term kidney function
• Amputees or people with unusual body composition

Frequently Asked Questions About eGFR

Common questions about eGFR, kidney function, and creatinine — answered by Sineth Hospitals.

What is eGFR and what does it measure? ▼

eGFR (Estimated Glomerular Filtration Rate) estimates how effectively your kidneys filter waste products from the blood, expressed as mL/min/1.73m². It is calculated using your serum creatinine level, age, and sex. It is one of the key tests used to assess kidney health and detect chronic kidney disease.

What is a normal eGFR value? ▼

An eGFR of 90 mL/min/1.73m² or above is generally considered normal in adults. Values between 60–89 indicate mildly reduced kidney function. Note that eGFR naturally declines slightly with age — a value in the 60–89 range in an elderly person may not always indicate disease.

Does a low eGFR always mean I have kidney disease? ▼

Not necessarily. Chronic kidney disease (CKD) is diagnosed when eGFR is persistently reduced for at least 3 months, or when other markers of kidney damage are present (such as protein in the urine). A single low eGFR result — especially during an illness — may be temporary. Always discuss the result with your doctor.

Why does the calculator ask for my sex? ▼

Serum creatinine levels differ between males and females because of differences in average muscle mass. The CKD-EPI 2021 equation accounts for this by using slightly different thresholds and multipliers for males and females to produce a more accurate eGFR estimate.

My creatinine report says µmol/L — how do I know which unit to select? ▼

Look at the unit printed next to the number on your laboratory report. If it says "µmol/L" or "micromol/L" or "umol/L", select µmol/L in the calculator. If it says "mg/dL", select mg/dL. Sri Lankan laboratories typically report in µmol/L. If the number looks like 0.9 or 1.2, it is almost certainly mg/dL. If it looks like 80 or 110, it is almost certainly µmol/L. When in doubt, check the report header or contact your laboratory.

Can I use this calculator for a child? ▼

No. The CKD-EPI equation is validated only for adults aged 18 and above. Kidney function in children is calculated using different equations (such as the Schwartz formula) that account for growth and development. Please consult a paediatrician for kidney function assessment in children.

Why does age affect eGFR? ▼

Kidney filtration capacity naturally declines slightly with age. Older adults tend to have lower eGFR values compared to younger adults even with healthy kidneys. The CKD-EPI equation includes age as a variable to account for this natural decline and provide a more accurate estimate.

eGFR Calculator – Estimate Your Kidney Function