Calculate your eGFR using the CKD-EPI formula. Enter creatinine, age and sex — get your kidney function stage, CKD classification, and next steps | Calculator4U
Estimate kidney function with eGFR.
The GFR (Glomerular Filtration Rate) Calculator is the gold standard for assessing kidney function. GFR measures how much blood your kidneys filter per minute, expressed in mL/min/1.73m². This value determines the stage of chronic kidney disease (CKD) and guides essential clinical treatment decisions, medication dosing adjustments, and personalized lifestyle recommendations.
Your kidneys filter approximately 180 liters of blood daily, systematically removing metabolic waste products and excess fluid while retaining crucial systemic nutrients. When kidney function declines, these toxic waste products accumulate progressively in the bloodstream, leading to severe physiological complications. Early detection through regular GFR monitoring is crucial because CKD often has no noticeable symptoms until significant, irreversible structural damage has occurred. Leading risk factors include diabetes, high blood pressure, a family history of renal failure, and being over the age of 60.
This calculator utilizes the advanced CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation, which provides significantly higher accuracy than older mathematical frameworks like the MDRD formula, particularly for normal and mildly decreased kidney function ranges. The equation computes values using serum creatinine, age, and biological sex variables. Notably, race parameters were removed from the 2021 updated formula to optimize equity in clinical care frameworks.
Cr = serum creatinine in mg/dL. Results are natively output in mL/min/1.73m².
| Stage | GFR Range | Description | Recommended Clinical Action |
|---|---|---|---|
| 1 | ≥90 | Normal or high function | Monitor baseline, aggressively manage underlying risk factors |
| 2 | 60-89 | Mildly decreased function | Estimate structural progression velocity |
| 3a | 45-59 | Mildly-moderately decreased | Thoroughly assess secondary complications |
| 3b | 30-44 | Moderately-severely decreased | Actively treat clinical complications |
| 4 | 15-29 | Severely decreased function | Prepare infrastructure for kidney replacement therapy |
| 5 | <15 | Kidney failure | Initiate chronic dialysis or evaluation for transplant |
eGFR naturally declines approximately 1 mL/min/1.73m² per year after age 40 due to the normal physiological aging of nephrons (kidney filtering units). This means a 75-year-old with an eGFR of 65 may have completely normal age-adjusted kidney function—not Stage 2 CKD. The National Kidney Foundation recommends considering these age-adjusted normals alongside the standard CKD staging system:
| Age Group | Average Normal eGFR | Lower Limit of Normal | Clinical Note |
|---|---|---|---|
| 20–29 | 116 mL/min/1.73m² | >90 | Peak metabolic kidney function |
| 30–39 | 107 mL/min/1.73m² | >90 | Slight natural senescence begins |
| 40–49 | 99 mL/min/1.73m² | >90 | ~1 mL/min/year structural decline |
| 50–59 | 93 mL/min/1.73m² | >75 | Decline accelerates slightly across metrics |
| 60–69 | 85 mL/min/1.73m² | >65 | eGFR values between 65–89 may be age-normal |
| 70+ | 75 mL/min/1.73m² | >55 | eGFR values between 60–75 are often age-normal |
If you received a creatinine result from a recent blood panel, use this table to understand the approximate corresponding eGFR for a 55-year-old individual. Use the calculator input fields above for your exact age and sex.
| Serum Creatinine (mg/dL) | Approx. eGFR (Male, 55y) | Approx. eGFR (Female, 55y) | CKD Stage Spectrum |
|---|---|---|---|
| 0.8 | 98 | 89 | Stage 1–2 |
| 1.0 | 81 | 74 | Stage 2 |
| 1.2 | 67 | 62 | Stage 2 |
| 1.5 | 51 | 47 | Stage 3a |
| 2.0 | 36 | 33 | Stage 3b |
| 3.0 | 22 | 20 | Stage 4 |
| 5.0+ | <15 | <15 | Stage 5 (Renal Failure) |
A 55-year-old man presenting with a serum creatinine of 1.2 mg/dL calculates out to an eGFR of approximately 72 mL/min/1.73m². This maps directly onto Stage 2 CKD (mildly decreased). Standard medical practice recommends routine annual monitoring to follow the stability of filtration rates.
Diabetes is the leading cause of kidney failure in the US, responsible for 38% of all new chronic dialysis admissions annually (USRDS 2023). Diabetic nephropathy typically progresses silently—many patients reach CKD Stage 3 before any recognizable clinical symptoms surface. The American Diabetes Association (ADA) mandates annual eGFR testing alongside urine albumin-to-creatinine ratio (UACR) profiles for all adults managing Type 1 or Type 2 diabetes. An eGFR calculation falling below 60 in a diabetic patient warrants immediate nephrology referral and structural medication review. For example, metformin requires careful down-dosing once eGFR drops below 45, and becomes strictly contraindicated once values fall below 30.
Sources & Methodology: Mathematical formula sourced directly from Inker LA, et al. "New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race." New England Journal of Medicine 2021;385:1737–1749. Calculator models validated strictly against the joint NKF-ASN Task Force recommendations. Staging reference guidelines align with the Kidney Disease: Improving Global Outcomes (KDIGO) consensus indicators. Content revised and updated May 2026. This electronic calculation is an estimating asset and does not act as a substitute for professional clinical medical advice.
eGFR is calculated using the 2021 CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation: eGFR = 142 × min(Cr/κ, 1)^α × max(Cr/κ, 1)^-1.200 × 0.9938^Age × (1.012 if female). Where Cr = serum creatinine in mg/dL; κ = 0.7 (female) or 0.9 (male); α = -0.241 (female) or -0.302 (male). Race was removed from the formula in 2021 to improve equity in clinical care — previously, a race correction factor was applied, which the NKF-ASN Task Force determined was not biologically justified. The formula requires only a standard blood creatinine test, age, and sex — all available from a basic metabolic panel.
Normal eGFR is above 90 mL/min/1.73m² for adults under 40. However, eGFR naturally declines approximately 1 mL/min/year after age 40 due to normal nephron aging. Age-adjusted normals: age 50–59 average 93; age 60–69 average 85; age 70+ average 75. A 70-year-old with eGFR 68 may have normal age-adjusted kidney function — not CKD Stage 2 — despite falling in the "mildly decreased" range. The National Kidney Foundation recommends interpreting eGFR alongside urine albumin, blood pressure, and clinical history, not as a standalone number. Always discuss your result with your physician.
The most common causes of chronically low eGFR (CKD) in the US are diabetes (38% of kidney failure cases), high blood pressure (26%), and glomerulonephritis. Diabetes damages the kidney's small blood vessels (diabetic nephropathy); hypertension damages larger renal arteries over decades. Less common causes: polycystic kidney disease, lupus nephritis, IgA nephropathy, and obstructive uropathy. Acute (temporary) causes of low eGFR include dehydration, NSAIDs (ibuprofen, naproxen), IV contrast dye, ACE inhibitors in high-risk patients, and infections. A single low reading does not diagnose CKD — KDIGO guidelines require two eGFR readings below 60, at least 3 months apart, for CKD diagnosis.
An eGFR of exactly 60 mL/min/1.73m² sits at the boundary between CKD Stage 2 (mildly decreased, 60–89) and Stage 3a (mildly-moderately decreased, 45–59). A single reading of 60 is not immediately alarming — it requires confirmation with a second test at least 3 months later and evaluation of urine albumin. For a 70-year-old, eGFR 60 may be age-normal. For a 40-year-old, eGFR 60 warrants investigation. If confirmed below 60 on two readings, your physician will monitor for complications (anemia, bone disease, acidosis), review medications for dose adjustment, and assess cardiovascular risk. eGFR 60 does not mean dialysis is needed — Stage 3 CKD patients are monitored carefully, often for years before progression.
Average eGFR decline rates vary by CKD stage and underlying cause. In Stage 3 CKD without intervention: approximately 2–4 mL/min/year. In Stage 4: 4–6 mL/min/year. Diabetic nephropathy progresses faster: 4–12 mL/min/year without treatment. With optimal blood pressure control (target <130/80 per 2024 KDIGO guidelines), RAAS blockade (ACE inhibitors or ARBs), SGLT2 inhibitors (shown to reduce CKD progression by 30–40% in trials), and low-protein diet, progression can be slowed to 1–2 mL/min/year. This is why early detection and treatment of CKD is critical — slowing progression from Stage 3 to Stage 5 can add decades before dialysis is needed. Ask your nephrologist about your personal rate of decline.
GFR (Glomerular Filtration Rate) is the actual rate at which your kidneys filter blood — it can only be measured directly using inulin clearance or iothalamate infusion, which are expensive research procedures. eGFR (estimated GFR) is a calculated estimate using blood creatinine, age, and sex via the CKD-EPI formula — it's what labs report on standard blood panels. eGFR is accurate within 30% of true GFR in most patients, which is sufficient for CKD staging and monitoring. The terms are often used interchangeably in clinical settings. Importantly, eGFR can be falsely high in patients with very low muscle mass (elderly, amputees) and falsely low in very muscular individuals — cystatin C is a more accurate alternative in these cases.
An eGFR of 60–89 (CKD Stage 2 — "mildly decreased") is not immediately worrying, but warrants attention and monitoring. Key questions: (1) Is there protein in your urine (UACR test)? Proteinuria with eGFR 60–89 confirms CKD and raises cardiovascular risk significantly. (2) Is your eGFR declining over time? One stable reading of 75 for 5 years is very different from a drop from 89 to 75 in 12 months. (3) How old are you? eGFR 75 in a 70-year-old is age-normal; in a 35-year-old it warrants nephrology evaluation. (4) Do you have diabetes or hypertension? Either condition with eGFR 60–89 requires more aggressive management. The American Kidney Fund recommends annual eGFR monitoring for anyone in Stage 2.