Yes, sometimes. eGFR can rise again if the cause was short-term, such as: Dehydration or a stomach bug An infection or hospital stay Medicines like NSAIDs (ibuprofen, naproxen) 9 A big meat meal or creatine supplements before the blood draw 4 If kidney tissue is scarred from long-term damage, the loss is usually permanent. Good blood pressure and blood sugar control can still slow the decline. 4

CKD-EPI Calculator - 2021 & 2009 eGFR, Cystatin C, Staging

Q: What is a normal eGFR for my age?

In adults, a normal eGFR is usually more than 90, and eGFR goes down with age even in people without kidney disease. 6 Average eGFR by age: Age 20–29: 116 Age 30–39: 107 Age 40–49: 99 Age 50–59: 93 Age 60–69: 85 Age 70+: 75 6 These are averages, not rules. An eGFR under 60 that lasts more than 3 months counts as chronic kidney disease at any age. 4

Q: Is an eGFR of 60 bad?

60 is the cut-off line. At or just above 60, many people have normal kidneys, especially older adults. But if your eGFR stays under 60 for more than 3 months , that is chronic kidney disease (stage G3a). 4 A single reading near 60 is not a diagnosis. Your doctor will repeat the test and check your urine for protein before deciding.

Q: What is the difference between CKD-EPI and MDRD?

Both turn creatinine into an eGFR, but CKD-EPI is newer and better. MDRD (1999): tends to underestimate kidney function above 60. 2 CKD-EPI (2009): about as accurate as MDRD below 60 and more accurate above it. 2 That accuracy lets labs report an exact number above 60 instead of only “60 or more.” 7 CKD-EPI (2021): the creatinine equation refitted without race. 1 In a national survey sample, CKD-EPI put the share of US adults with chronic kidney disease at 11.5%, against 13.1% with MDRD. 2

Q: At what eGFR do you need dialysis?

Dialysis is usually started because of symptoms and lab results, and this often happens when eGFR is between 5 and 10 . 4 The number alone does not decide it. Doctors also look at signs such as loss of appetite, itching, confusion, fluid or blood pressure that cannot be controlled, and high potassium or acid levels that medicine cannot fix. 4 Planning for dialysis or a transplant starts earlier, when eGFR falls below about 15 to 20. 4

Q: At what eGFR should you see a kidney specialist?

KDIGO suggests seeing a kidney specialist if you have any of these: eGFR under 30 A 5-year risk of kidney failure above 3% to 5% on a validated risk equation A lasting drop in eGFR of more than 20% Urine albumin-to-creatinine ratio above 700 mg/g , or 300 mg/g or more together with blood in the urine Red blood cell casts, or more than 20 red blood cells per high-power field, in the urine with no clear cause Kidney stones that keep coming back High blood pressure that will not come down on 4 or more drugs 4

Q: How can I lower my creatinine and raise my eGFR?

Steps that help protect kidney function: Keep systolic blood pressure under 120 if your doctor says it is safe for you Keep blood sugar in range if you have diabetes Keep sodium under 2 grams a day Avoid tobacco Avoid regular NSAIDs like ibuprofen, which can injure the kidneys 4 Drink enough water, but do not overdo it Creatine supplements and high-protein diets raise creatinine without harming the kidneys, so stopping them can lower it. 4 Ask your doctor about SGLT2 inhibitors and ACE inhibitors or ARBs. Trials show these drugs slow kidney decline. 4

Q: Does dehydration affect eGFR?

Yes. When you are dry, creatinine builds up in the blood and eGFR drops. 10 This is usually temporary, and the number goes back up after you drink fluids. That is one reason doctors repeat a low result before diagnosing kidney disease. 4

Q: Do you need to fast before a creatinine blood test?

No, fasting is not needed for creatinine or cystatin C. But a few things can shift the result, so it helps to: Avoid meat or fish for at least 12 hours before the test 4 Avoid very hard exercise just before the test Tell your doctor if you take creatine supplements 4 Drink normally, not extra If the test is bundled with cholesterol or glucose, your doctor may still ask you to fast for those.

Q: Why is my creatinine normal but my eGFR low?

Because eGFR uses more than creatinine. It also uses your age and sex. Creatinine comes from muscle, and the level varies with a person's size and muscle mass. 10 Older adults, women, and thin people make less of it, so a "normal" creatinine of 1.0 mg/dL can still mean a low eGFR for them. With the 2021 equation, a 75-year-old woman with a creatinine of 1.0 mg/dL has an eGFR of about 59, while a 30-year-old man with the same value has about 104.

KDIGO GFR categories — the row matching your current result is highlighted and outlined.
Stage	eGFR Range	Description	Key Actions
G1	≥ 90 mL/min/1.73 m²	Normal or high	Treat underlying risk factors; confirm CKD diagnosis with uACR
G2	60–89 mL/min/1.73 m²	Mildly decreased	Monitor annually; optimize blood pressure and glucose control
G3a	45–59 mL/min/1.73 m²	Mildly to moderately decreased	Consider nephrology consult; initiate SGLT2 inhibitor if diabetic nephropathy
G3b	30–44 mL/min/1.73 m²	Moderately to severely decreased	Nephrology referral; review and adjust nephrotoxic medications
G4	15–29 mL/min/1.73 m²	Severely decreased	Prepare for renal replacement therapy; evaluate for kidney transplant
G5	< 15 mL/min/1.73 m²	Kidney failure	Initiate dialysis or pursue kidney transplant

KDIGO GFR categories — the row matching your current result is highlighted and outlined.

Stage

eGFR Range

Description

Key Actions

≥ 90 mL/min/1.73 m²

Normal or high

Treat underlying risk factors; confirm CKD diagnosis with uACR

60–89 mL/min/1.73 m²

Mildly decreased

Monitor annually; optimize blood pressure and glucose control

G3a

45–59 mL/min/1.73 m²

Mildly to moderately decreased

Consider nephrology consult; initiate SGLT2 inhibitor if diabetic nephropathy

G3b

30–44 mL/min/1.73 m²

Moderately to severely decreased

Nephrology referral; review and adjust nephrotoxic medications

15–29 mL/min/1.73 m²

Severely decreased

Prepare for renal replacement therapy; evaluate for kidney transplant

< 15 mL/min/1.73 m²

Kidney failure

Initiate dialysis or pursue kidney transplant

Introduction

This CKD-EPI calculator estimates how well your kidneys clean your blood. The result is called eGFR, short for estimated glomerular filtration rate. A higher number means your kidneys are filtering better. A lower number can be a sign of chronic kidney disease (CKD).

To get your eGFR, enter your age, biological sex, and a lab value. Most people use serum creatinine. Some labs also test cystatin C, which is less affected by muscle size.⁴ You can pick from five CKD-EPI equations, including the newer 2021 versions that do not use race.¹

The tool shows your eGFR, your KDIGO kidney stage (G1 to G5), and each step of the math. You can switch units for both your lab values and your result. A chart also compares your eGFR across all five equations at once.

This calculator is for learning and general guidance only. It does not replace a visit with your doctor. Talk to a health care provider about your lab results and what they mean for you.

How to use our CKD-EPI Calculator

Enter a few lab and patient details, and this CKD-EPI calculator gives you an estimated glomerular filtration rate (eGFR) plus the matching KDIGO kidney stage, a step-by-step solution, and a chart comparing all CKD-EPI equations.

Select CKD-EPI Equation: Pick the formula you want to use. The 2021 CKD-EPI Creatinine equation is the default and is race-free. Your choice decides which input fields show up below.

Biological Sex: Choose Female or Male. This is sex at birth, not gender identity, because the formula uses different constants for each.

Age: Type the patient's age in whole years. It must be between 18 and 110, since CKD-EPI is only for adults.

Serum Creatinine: Enter the blood creatinine result and pick mg/dL or μmol/L from the drop-down. Valid range is 0.1 to 30 mg/dL. Switching units converts the number for you.

Cystatin C: For cystatin C equations, enter the result and choose mg/L, mg/dL, or μg/L. Valid range is 0.1 to 15 mg/L.

Race: This only shows for the older 2009 and 2012 equations. Choose Black or Non-Black. The 2021 equations do not use race and are preferred today.⁷

Display eGFR in: Choose how to show the answer: mL/min/1.73 m² (standard), mL/s/1.73 m² (SI), or L/day/1.73 m². Kidney stages are always based on mL/min/1.73 m².

Click Calculate to see your eGFR and CKD stage. Click Reset to return to the sample values.

What Is eGFR?

eGFR stands for estimated glomerular filtration rate. It is a number that shows how well your kidneys clean waste from your blood. Your kidneys have tiny filters called glomeruli. eGFR estimates how much blood those filters clean each minute, adjusted for a standard body size of 1.73 m².⁸ A higher number means better kidney function.

What Is the CKD-EPI Equation?

CKD-EPI stands for Chronic Kidney Disease Epidemiology Collaboration. It is a set of formulas that turn a blood test result into an eGFR number. Doctors use it because measuring true GFR directly is a long and complex process.⁶ The KDIGO 2012 guideline recommended the 2009 CKD-EPI creatinine equation for adults, and the 2024 update says race should not be used in eGFR.⁴

Blood Tests Used

Serum creatinine: a waste product made by your muscles. Healthy kidneys remove it. When creatinine goes up, eGFR goes down. Muscle mass, diet, and some drugs can change it.⁴
Cystatin C: a protein made by almost every cell in your body. It is less affected by muscle mass and diet, so it can help for people with very high or very low muscle mass.⁴
Both together: using creatinine and cystatin C in one equation gives the most accurate estimate and is recommended when the result will change treatment.⁷

Age and sex are also part of the formula because they change how much creatinine and cystatin C your body normally makes.

Why Race Was Removed

Older CKD-EPI equations from 2009 and 2012 added a race factor for Black patients.⁵ In 2021, a task force of the National Kidney Foundation and the American Society of Nephrology recommended equations without it, noting that race is a social label, not a biological measure.⁵ The old factor could delay care for Black patients. The 2021 equations are race-free and are preferred today.⁴ The older versions are kept here only for comparing past lab reports.

CKD Stages by eGFR

KDIGO sorts kidney function into six GFR categories:

G1: 90 or higher (normal or high)
G2: 60 to 89 (mildly decreased)
G3a: 45 to 59 (mildly to moderately decreased)
G3b: 30 to 44 (moderately to severely decreased)
G4: 15 to 29 (severely decreased)
G5: under 15 (kidney failure)⁴

An eGFR of 90 or higher alone does not rule out kidney disease.⁴ A doctor also checks protein in the urine, usually with a urine albumin-to-creatinine ratio (uACR). Chronic kidney disease is diagnosed when signs of kidney damage or a low eGFR last more than three months.⁴

What Can Change Your Result

eGFR is an estimate, not an exact measure.⁷ It can be off if you have very high or very low muscle mass, are an amputee, eat lots of meat or take creatine supplements before the test, or are very ill.⁴ Pregnancy can also affect it.⁶ It is also less reliable when kidney function is changing quickly. Some medicines, such as trimethoprim and cimetidine, can affect the creatinine result.¹⁰ A single low reading should always be repeated before any diagnosis.⁴

Units

Most labs report eGFR in mL/min/1.73 m². SI units use mL/s/1.73 m² (divide by 60). Creatinine may be reported in mg/dL or µmol/L (1 mg/dL = 88.42 µmol/L). Cystatin C is usually mg/L.

This information is for education only. Talk to a doctor or nephrologist about your own test results and treatment.

Formulas used

2021 CKD-EPI Creatinine eGFR ¹

eGFR = 142 \times \min\!\left(\frac{S_{cr}}{\kappa},1\right)^{\alpha} \times \max\!\left(\frac{S_{cr}}{\kappa},1\right)^{-1.200} \times 0.9938^{\,\text{age}} \times \left(1.012 \text{ if female}\right)

2021 CKD-EPI Creatinine–Cystatin C eGFR ¹

eGFR = 135 \times \min\!\left(\frac{S_{cr}}{\kappa},1\right)^{\alpha} \times \max\!\left(\frac{S_{cr}}{\kappa},1\right)^{-0.544} \times \min\!\left(\frac{CysC}{0.8},1\right)^{-0.323} \times \max\!\left(\frac{CysC}{0.8},1\right)^{-0.778} \times 0.9961^{\,\text{age}} \times \left(0.963 \text{ if female}\right)

2009 CKD-EPI Creatinine eGFR ²

eGFR = 141 \times \min\!\left(\frac{S_{cr}}{\kappa},1\right)^{\alpha} \times \max\!\left(\frac{S_{cr}}{\kappa},1\right)^{-1.209} \times 0.993^{\,\text{age}} \times \left(1.018 \text{ if female}\right) \times \left(1.159 \text{ if Black}\right)

2012 CKD-EPI Cystatin C eGFR ³

eGFR = 133 \times \min\!\left(\frac{CysC}{0.8},1\right)^{-0.499} \times \max\!\left(\frac{CysC}{0.8},1\right)^{-1.328} \times 0.996^{\,\text{age}} \times \left(0.932 \text{ if female}\right)

2012 CKD-EPI Creatinine–Cystatin C eGFR ³

eGFR = 135 \times \min\!\left(\frac{S_{cr}}{\kappa},1\right)^{\alpha} \times \max\!\left(\frac{S_{cr}}{\kappa},1\right)^{-0.601} \times \min\!\left(\frac{CysC}{0.8},1\right)^{-0.375} \times \max\!\left(\frac{CysC}{0.8},1\right)^{-0.711} \times 0.995^{\,\text{age}} \times \left(0.969 \text{ if female}\right) \times \left(1.08 \text{ if Black}\right)

Creatinine unit conversion

S_{cr}\,[\text{mg/dL}] = \frac{S_{cr}\,[\mu\text{mol/L}]}{88.42}

Cystatin C unit conversion

CysC\,[\text{mg/L}] = CysC\,[\text{mg/dL}] \times 10 = \frac{CysC\,[\mu\text{g/L}]}{1000}

eGFR output unit conversion

eGFR_{\text{mL/s}} = \frac{eGFR_{\text{mL/min}}}{60}, \qquad eGFR_{\text{L/day}} = eGFR_{\text{mL/min}} \times 1.44

Frequently asked questions

What is a normal eGFR for my age?

In adults, a normal eGFR is usually more than 90, and eGFR goes down with age even in people without kidney disease.⁶ Average eGFR by age:

Age 20–29: 116
Age 30–39: 107
Age 40–49: 99
Age 50–59: 93
Age 60–69: 85
Age 70+: 75⁶

These are averages, not rules. An eGFR under 60 that lasts more than 3 months counts as chronic kidney disease at any age.⁴

Is an eGFR of 60 bad?

60 is the cut-off line. At or just above 60, many people have normal kidneys, especially older adults.

But if your eGFR stays under 60 for more than 3 months, that is chronic kidney disease (stage G3a).⁴ A single reading near 60 is not a diagnosis. Your doctor will repeat the test and check your urine for protein before deciding.

Can eGFR go back up?

Yes, sometimes. eGFR can rise again if the cause was short-term, such as:

Dehydration or a stomach bug
An infection or hospital stay
Medicines like NSAIDs (ibuprofen, naproxen)⁹
A big meat meal or creatine supplements before the blood draw⁴

If kidney tissue is scarred from long-term damage, the loss is usually permanent. Good blood pressure and blood sugar control can still slow the decline.⁴

What is the difference between CKD-EPI and MDRD?

Both turn creatinine into an eGFR, but CKD-EPI is newer and better.

MDRD (1999): tends to underestimate kidney function above 60.²
CKD-EPI (2009): about as accurate as MDRD below 60 and more accurate above it.² That accuracy lets labs report an exact number above 60 instead of only “60 or more.”⁷
CKD-EPI (2021): the creatinine equation refitted without race.¹

In a national survey sample, CKD-EPI put the share of US adults with chronic kidney disease at 11.5%, against 13.1% with MDRD.²

At what eGFR do you need dialysis?

Dialysis is usually started because of symptoms and lab results, and this often happens when eGFR is between 5 and 10.⁴

The number alone does not decide it. Doctors also look at signs such as loss of appetite, itching, confusion, fluid or blood pressure that cannot be controlled, and high potassium or acid levels that medicine cannot fix.⁴ Planning for dialysis or a transplant starts earlier, when eGFR falls below about 15 to 20.⁴

At what eGFR should you see a kidney specialist?

KDIGO suggests seeing a kidney specialist if you have any of these:

eGFR under 30
A 5-year risk of kidney failure above 3% to 5% on a validated risk equation
A lasting drop in eGFR of more than 20%
Urine albumin-to-creatinine ratio above 700 mg/g, or 300 mg/g or more together with blood in the urine
Red blood cell casts, or more than 20 red blood cells per high-power field, in the urine with no clear cause
Kidney stones that keep coming back
High blood pressure that will not come down on 4 or more drugs⁴

How can I lower my creatinine and raise my eGFR?

Steps that help protect kidney function:

Keep systolic blood pressure under 120 if your doctor says it is safe for you
Keep blood sugar in range if you have diabetes
Keep sodium under 2 grams a day
Avoid tobacco
Avoid regular NSAIDs like ibuprofen, which can injure the kidneys⁴
Drink enough water, but do not overdo it

Creatine supplements and high-protein diets raise creatinine without harming the kidneys, so stopping them can lower it.⁴

Ask your doctor about SGLT2 inhibitors and ACE inhibitors or ARBs. Trials show these drugs slow kidney decline.⁴

Does dehydration affect eGFR?

Yes. When you are dry, creatinine builds up in the blood and eGFR drops.¹⁰

This is usually temporary, and the number goes back up after you drink fluids. That is one reason doctors repeat a low result before diagnosing kidney disease.⁴

Do you need to fast before a creatinine blood test?

No, fasting is not needed for creatinine or cystatin C. But a few things can shift the result, so it helps to:

Avoid meat or fish for at least 12 hours before the test⁴
Avoid very hard exercise just before the test
Tell your doctor if you take creatine supplements⁴
Drink normally, not extra

If the test is bundled with cholesterol or glucose, your doctor may still ask you to fast for those.

Why is my creatinine normal but my eGFR low?

Because eGFR uses more than creatinine. It also uses your age and sex.

Creatinine comes from muscle, and the level varies with a person's size and muscle mass.¹⁰ Older adults, women, and thin people make less of it, so a "normal" creatinine of 1.0 mg/dL can still mean a low eGFR for them. With the 2021 equation, a 75-year-old woman with a creatinine of 1.0 mg/dL has an eGFR of about 59, while a 30-year-old man with the same value has about 104.

Can you have kidney disease with a normal eGFR?

Yes. eGFR only measures filtering speed. Kidney damage can show up in other ways:

Protein or albumin in the urine
Blood in the urine
Cysts or scarring on an ultrasound
Abnormal kidney biopsy⁴

This is why doctors order a urine albumin-to-creatinine ratio (uACR) along with the blood test. Early diabetic kidney disease often shows albumin in the urine years before eGFR drops.

What is the difference between eGFR and creatinine clearance?

They measure similar things but are used differently.

eGFR (CKD-EPI): adjusted to a standard body size of 1.73 m².⁸ Used to stage chronic kidney disease.
Creatinine clearance (Cockcroft-Gault): uses body weight and is not size-adjusted.¹¹ Still used on many drug labels for dosing.⁸

For a very large or very small person the two numbers can differ a lot, so pharmacists check which one a drug label asks for.

Which eGFR equation is the most accurate?

Equations that use both creatinine and cystatin C, such as the 2021 CKD-EPI creatinine–cystatin C equation, are more accurate than creatinine alone.⁷ Using two markers cancels out some of the error from each one.

Adding cystatin C matters most when the result is close to a decision point, such as drug dosing or a kidney transplant evaluation.⁷ It also helps when creatinine may mislead because of unusual muscle mass.⁴

How often should eGFR be checked?

It depends on your stage and how much albumin is in your urine. For people with chronic kidney disease, the KDIGO guideline suggests testing from once a year at the lowest-risk stages up to four or more times a year at stage G4 or G5.⁴

People at risk, such as those with diabetes, high blood pressure, or heart disease, should be tested with both a blood test for eGFR and a urine albumin test.⁴

Does eGFR change from day to day?

Yes, a little. Lab and body variation means a small change between two tests is often not a real change.

What matters is the trend over months and years.⁷ A lasting drop of more than 20% is one of the reasons to see a kidney specialist.⁴

Sources

CKD-EPI Calculator

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