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) A big meat meal or creatine supplements before the blood draw 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 a lot.

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

Q: What is a normal eGFR for my age?

Healthy young adults usually have an eGFR near 100 to 120 mL/min/1.73 m² . It slowly drops with age, about 1 point per year after age 30 to 40. Age 20–29: about 100–116 Age 40–49: about 90–99 Age 60–69: about 80–85 Age 70+: often 70–75 These are averages, not rules. An eGFR under 60 that lasts more than 3 months counts as chronic kidney disease at any age.

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). 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): underestimates kidney function above 60. Many labs only reported it as "greater than 60." CKD-EPI (2009, 2021): more accurate in people with near-normal kidneys, so it gives a real number above 60. KDIGO and most labs now use CKD-EPI. MDRD tends to label healthy people as having kidney disease.

Q: At what eGFR do you need dialysis?

Most people start dialysis when eGFR falls below 15 , and often closer to 5–10. The number alone does not decide it. Doctors also look at symptoms like nausea, swelling, trouble breathing, high potassium, and fluid that will not go away. Planning for dialysis or a transplant usually starts earlier, around an eGFR of 20.

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

KDIGO suggests a nephrology referral if you have any of these: eGFR under 30 A fast drop in eGFR (more than 5 points a year) Urine albumin-to-creatinine ratio over 300 mg/g Blood in the urine with no clear cause Kidney stones that keep coming back High blood pressure that will not come down on 4 drugs

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

Steps that help protect kidney function: Keep blood pressure near 120/80 Keep blood sugar in range if you have diabetes Drink enough water, but do not overdo it Cut back on salt and processed food Avoid regular NSAIDs like ibuprofen Stop creatine supplements and protein powders Quit smoking Ask your doctor about SGLT2 inhibitors and ACE inhibitors or ARBs. Trials show these drugs slow kidney decline.

Q: Does dehydration affect eGFR?

Yes. When you are dry, less blood flows through your kidneys. Creatinine builds up in the blood and eGFR drops. This is temporary. After you drink fluids, the number usually goes back up within days. That is one reason doctors never diagnose kidney disease from one low reading.

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: Skip a large meat meal the night before Avoid hard exercise for 24 hours Stop creatine supplements for a few days 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. 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. A 75-year-old woman with creatinine of 1.0 may have an eGFR near 55, while a 30-year-old man with the same value is near 95.

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. You can pick from five CKD-EPI equations, including the newer 2021 versions that do not use race.

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.

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. 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 slow and costly. CKD-EPI is now the standard formula for adults in most guidelines, including KDIGO.

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.
Cystatin C: a protein made by almost every cell in your body. It is less affected by muscle mass, diet, and age, so it can be more accurate for very muscular, very thin, older, or sick people.
Both together: using creatinine and cystatin C in one equation gives the most accurate estimate and is recommended when the result will change treatment.

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. In 2021, the National Kidney Foundation and the American Society of Nephrology removed it. Race is a social label, not a biological measure of kidney function, and the old factor could delay care for Black patients. The 2021 equations are race-free and are preferred today. 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)

An eGFR of 90 or higher alone does not rule out kidney disease. 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.

What Can Change Your Result

eGFR is an estimate, not an exact measure. It can be off if you have very high or very low muscle mass, are an amputee, are pregnant, eat lots of meat or take creatine supplements before the test, are very ill, or have rapidly changing kidney function. Some medicines, such as trimethoprim and cimetidine, raise creatinine without harming the kidneys. A single low reading should always be repeated before any diagnosis.

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

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

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

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

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

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?

Healthy young adults usually have an eGFR near 100 to 120 mL/min/1.73 m². It slowly drops with age, about 1 point per year after age 30 to 40.

Age 20–29: about 100–116
Age 40–49: about 90–99
Age 60–69: about 80–85
Age 70+: often 70–75

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

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). 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)
A big meat meal or creatine supplements before the blood draw

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 a lot.

What is the difference between CKD-EPI and MDRD?

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

MDRD (1999): underestimates kidney function above 60. Many labs only reported it as "greater than 60."
CKD-EPI (2009, 2021): more accurate in people with near-normal kidneys, so it gives a real number above 60.

KDIGO and most labs now use CKD-EPI. MDRD tends to label healthy people as having kidney disease.

At what eGFR do you need dialysis?

Most people start dialysis when eGFR falls below 15, and often closer to 5–10.

The number alone does not decide it. Doctors also look at symptoms like nausea, swelling, trouble breathing, high potassium, and fluid that will not go away. Planning for dialysis or a transplant usually starts earlier, around an eGFR of 20.

At what eGFR should you see a kidney specialist?

KDIGO suggests a nephrology referral if you have any of these:

eGFR under 30
A fast drop in eGFR (more than 5 points a year)
Urine albumin-to-creatinine ratio over 300 mg/g
Blood in the urine with no clear cause
Kidney stones that keep coming back
High blood pressure that will not come down on 4 drugs

How can I lower my creatinine and raise my eGFR?

Steps that help protect kidney function:

Keep blood pressure near 120/80
Keep blood sugar in range if you have diabetes
Drink enough water, but do not overdo it
Cut back on salt and processed food
Avoid regular NSAIDs like ibuprofen
Stop creatine supplements and protein powders
Quit smoking

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

Does dehydration affect eGFR?

Yes. When you are dry, less blood flows through your kidneys. Creatinine builds up in the blood and eGFR drops.

This is temporary. After you drink fluids, the number usually goes back up within days. That is one reason doctors never diagnose kidney disease from one low reading.

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:

Skip a large meat meal the night before
Avoid hard exercise for 24 hours
Stop creatine supplements for a few days
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. 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. A 75-year-old woman with creatinine of 1.0 may have an eGFR near 55, while a 30-year-old man with the same value is near 95.

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 biopsy

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. Used to stage chronic kidney disease.
Creatinine clearance (Cockcroft-Gault): uses body weight and is not size-adjusted. Still used on many drug labels for dosing.

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?

The 2021 CKD-EPI creatinine–cystatin C equation is the most accurate. Using two markers cancels out some of the error from each one.

Guidelines suggest adding cystatin C when the result will change care, such as before starting a risky drug, judging transplant eligibility, or when creatinine seems unreliable because of unusual muscle mass.

How often should eGFR be checked?

It depends on your stage and how much albumin is in your urine. A common schedule:

G1–G2 (60+): once a year
G3a (45–59): once or twice a year
G3b (30–44): two to three times a year
G4 (15–29): three times a year
G5 (under 15): four or more times a year

People with diabetes, high blood pressure, or heart disease should be screened at least yearly even with normal results.

Does eGFR change from day to day?

Yes, a little. Normal lab and body variation can move eGFR by about 5 to 10 percent between tests. A shift from 58 to 62 is usually noise, not real change.

What matters is the trend over months and years. A steady drop of more than 5 points per year is a warning sign worth acting on.

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