How do I calculate how fast my eGFR is dropping?

Take **two eGFR values** from the **same equation** (ideally the same lab) and the **months between draws**. Annualized slope ≈ **(eGFR_now − eGFR_prior) ÷ (months ÷ 12)**. Example: **52 → 45** over **18 months** → (45−52)/1.5 = **−4.7 mL/min/1.73 m² per year**. Enter values in the calculator above for **G-stage**, **5-year linear eGFR** (if slope is negative), and rough **years to cross 30 or 15** on a straight line. Real kidneys rarely follow a straight line—repeat labs and treat the cause.

Is “years to eGFR 15” the same as when I will start dialysis?

**No.** **eGFR 15** is a **staging number** (G5 range), not a dialysis start date. People start **hemodialysis, peritoneal dialysis, or pursue transplant** because of **symptoms and complications**—volume overload, hyperkalemia, metabolic acidosis, uremic symptoms, malnutrition—or shared decision-making at higher eGFR. Some patients remain off dialysis for a time even below 15 with careful management. This calculator’s horizon lines are **arithmetic only** for classroom-style understanding of slope.

Why does the calculator show years to 30 as well as 15?

**eGFR 30** marks **G3b/G4 boundary**—a common checkpoint for **CKD education**, **medication reconciliation**, **vaccination**, **anemia and bone-mineral labs**, and **access planning discussions** in many practices. Crossing 30 on a **projected line** does not mean imminent dialysis; it means you may enter a phase where **nephrology co-management** intensifies. **15** is a lower numeric target used in teaching to illustrate how fast a given slope would reach kidney-failure **staging** if unchanged—which is often **not** unchanged after treatment.

Why is linear CKD progression often wrong?

CKD trajectories **curve**: they can **plateau** for years after blood pressure control, **ACE inhibitor/ARB** or **SGLT2 inhibitor** therapy (when appropriate), or **nephrotoxin removal**. They can **accelerate** with **AKI on CKD**, **intercurrent illness**, or **progressive glomerular disease**. **Two creatinine points** cannot detect nonlinearity, **regression to the mean**, or **lab noise** (±2–5 mL/min/1.73 m² is common). Cohort studies show **wide heterogeneity**—always interpret slope with **≥3 timed values**, **urine albumin**, and **clinical context**.

Which eGFR equation should I use for progression?

Use whatever your **lab reports consistently** over time—often **CKD-EPI creatinine 2021 (race-free)** in the U.S., sometimes **CKD-EPI 2009**, **MDRD**, or **cystatin C–based eGFR** elsewhere. **Mixing equations** between dates invalidates slope. **Creatinine** rises with **muscle mass**, **protein supplements**, and some drugs (**trimethoprim**, **cimetidine**); it falls with **malnutrition** and **amputation**—sometimes eGFR “improves” while true GFR worsens. Estimate a single point with our **GFR calculator**, then return here when you have **two comparable lab dates**.

What CKD stage is eGFR 45 or 60?

By **KDIGO G category** (eGFR alone): **45** = **G3a** (45–59); **60** = **G2** (60–89). Staging is **incomplete without albuminuria (A1–A3)** and **cause** (diabetic kidney disease, hypertension, glomerulonephritis, etc.). **G3a** often triggers **more frequent monitoring** and **cardiovascular risk reduction**; **G2** may still be significant if **ACR is elevated**. The table on this page lists all G bands—your clinician assigns **full CKD classification**.

How does proteinuria (albuminuria) change progression risk?

**Higher urine albumin-to-creatinine ratio (ACR)** predicts **faster GFR loss** and **more cardiovascular events** independent of baseline eGFR. KDIGO uses a **heatmap** combining **G and A** categories: the same eGFR 45 with **ACR 300** is different prognosis. This page **does not input ACR**—ask for **urine albumin** on the same lab order as creatinine. **ACE inhibitors/ARBs** and selected **SGLT2 inhibitors** are often discussed when albuminuria and CKD align with guidelines—prescribing is clinician-only.

Can eGFR improve on follow-up labs?

**Yes.** Treating **hypertension**, **diabetes**, **obstruction**, **volume depletion**, or stopping **nephrotoxins** (NSAIDs, certain contrast exposures) can raise eGFR. **Recovery from AKI** superimposed on CKD can look like a **positive slope**. If annualized change is **≥0**, this tool **does not project years to 15/30** downward—instead note **stabilization** and focus on **maintaining therapy**. A single improved lab should be **confirmed** before assuming reversal.

What is assumed annual decline mode for?

When you lack two dated eGFRs, **assumed-decline mode** applies a **hypothetical loss** (e.g. **−2 or −3 mL/min/1.73 m²/year**) to show **arithmetic consequences**—useful for **patient education analogies** or **exam questions**, not to invent a patient-specific slope without data. If your clinician says “typical diabetic CKD might lose ~3–5 per year untreated,” that is **population language**, not your guaranteed trajectory. Prefer **two-point mode** with real lab dates whenever possible.

When should I be referred to nephrology?

Common triggers (simplified): **eGFR <30**, **rapid decline**, **ACR ≥300 mg/g**, **nephrotic syndrome**, **persistent hematuria with proteinuria**, **PKD**, **suspected glomerulonephritis**, **difficult hypertension or hyperkalemia**, and **CKD in pregnancy planning**. Primary care often co-manages **G3a** with stable albuminuria—thresholds vary by health system. **Do not wait** for a projected “years to 15” number if you have **red-flag symptoms** (edema, dyspnea, confusion, anuria).

Does this calculator work for children?

**No.** Pediatric CKD uses **Schwartz and other height-based GFR estimates**, different **staging nuances**, and **growth** considerations. Use our **GFR calculator** in pediatric mode for a point estimate; progression assessment belongs with **pediatric nephrology** using serial measured GFR or validated pediatric equations—not adult two-point linear extrapolation.

Is this kidney disease progression calculator medical advice?

**No.** It performs **linear slope arithmetic** and **eGFR-only G staging** for education. It does not diagnose **AKI vs CKD**, prescribe medications, or schedule dialysis. Decisions require **licensed clinicians**, **repeat labs**, **imaging**, and **shared goals of care**. Seek urgent care for **unable to urinate**, **severe shortness of breath**, **chest pain**, or **altered mental status** with known kidney disease.

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Nephrology & CKD education

Kidney Disease Progression Calculator

Estimate CKD stage (G1–G5) from your current eGFR, compute annualized eGFR slope from two timed labs, and see educational years to 30 or 15 on a straight line—plus assumed decline mode when you only have one value. Not dialysis timing; real curves change with blood pressure, albuminuria, and therapy. More on our medical calculators hub.

Last updated: June 4, 2026

Two-point slope or assumed annual eGFR loss

KDIGO-style G staging from current eGFR

Explicit limits: no ACR, no dialysis scheduling

Kidney disease progression

Linear eGFR slope from two labs or an assumed annual loss—education only, not dialysis planning.

Projection mode

Current eGFR (mL/min/1.73 m²)

Prior eGFR (older value)

Months between measurements

CKD stage (by current eGFR)

G3a

G3a — eGFR 45–59

Annualized eGFR change

-4.67 / year

Negative values mean average loss per year over the window you supplied (or the assumed slope).

Linear teaching projection (not a clinical date)

Rough years to 15 mL/min/1.73 m² if slope stayed constant: 6.4

Rough years to 30: 3.2

If the same straight line continued 5 years: eGFR ≈ 21.7

Linear extrapolation is a teaching simplification. Your nephrology team uses trends, proteinuria, comorbidities, and shared decision-making—not a single projected date.

KDIGO CKD heatmaps show wide individual trajectories; linear fit to two labs can mislead if one value was acute illness, dehydration, or medication change.
Albuminuria/creatinine ratio, blood pressure control, renin-angiotensin blockade (when appropriate), SGLT2 inhibitors in selected patients, and cause-specific care change slope—this page does not capture those levers.
Dialysis or transplant referral thresholds depend on symptoms, potassium, acid-base, volume overload, and nutrition—not eGFR alone.

Educational linear model only. CKD progression is often nonlinear. Dialysis and transplant timing depend on symptoms and labs—not crossing eGFR 15 on a calculator. Always add urine albumin-to-creatinine ratio with your clinician.

Example projections (from calculator logic)

52 → 45 · 18 mo

-4.67 / yr

G3a · ~3.2 yr to 30 · ~6.4 yr to 15

72 → 68 · 24 mo

-2 / yr

G2 · slower decline

eGFR 38 · −3/yr assumed

~2.7 yr to 30

G3b · classroom-style input

35 → 22 · 12 mo

-13 / yr

G4 · ~0.5 yr to 15 if linear

CKD G-stage by eGFR (KDIGO — G category only)

Stage	eGFR (mL/min/1.73 m²)	Teaching meaning
G1	≥90	Normal or high; kidney damage may still exist (albuminuria, hematuria, imaging)
G2	60–89	Mildly decreased; monitor trend and cardiovascular risk
G3a	45–59	Mild to moderate decrease; many guidelines discuss nephrology co-management
G3b	30–44	Moderate to severe; medication dosing and complication screening intensify
G4	15–29	Severe; prepare for renal replacement therapy education when appropriate
G5	<15	Kidney failure range; dialysis/transplant decisions are clinical, not formula-based

Albuminuria (A) categories — needed for full KDIGO risk

This progression tool uses eGFR only. Ask your clinician for urine ACR on the same lab requisition as creatinine.

Category	Urine ACR	Progression context
A1 — Normal to mildly increased	<30 mg/g	Lower progression risk when eGFR stable
A2 — Moderately increased	30–300 mg/g	Moderate risk; ACEi/ARB and BP targets often emphasized
A3 — Severely increased	>300 mg/g	Higher progression and cardiovascular risk—needs specialist input

Interpreting annualized eGFR change (teaching bands)

Slope (approx.)	How teams often frame it
0 to −2 mL/min/1.73 m²/yr	Relatively slow in many cohorts—still monitor cause and albuminuria
−2 to −5	Common “moderate” decline range in teaching examples—therapy may bend curve
−5 to −10	Faster decline—often warrants expedited evaluation and adherence review
< −10	Rapid loss—exclude AKI on CKD, obstruction, relapse; urgent nephrology context

Annualized ΔeGFR = (eGFR_now − eGFR_prior) ÷ (months_between ÷ 12)

If ΔeGFR < 0 and current > target: years_to_target ≈ (current − target) ÷ |ΔeGFR|

Assumed-decline mode sets ΔeGFR = −(magnitude you enter) per year.

Common nephrology referral themes (simplified)

•eGFR <30 mL/min/1.73 m² (G4) or persistent rapid decline
•Urine ACR ≥300 mg/g (A3) or nephrotic-range proteinuria
•eGFR drop >25% within a year or unexplained hematuria
•Resistant hypertension, recurrent hyperkalemia, or refractory acidosis
•Known polycystic kidney disease, glomerulonephritis, or systemic disease affecting kidneys
•Pregnancy planning with moderate–advanced CKD

What this calculator does not model

•KDIGO combined G+A risk heatmap (requires urine albumin)
•Cystatin C–based eGFR or creatinine assay drift between labs
•Acute kidney injury recovery superimposed on CKD
•Competing mortality, transplant, or modality-specific survival models

How CKD progression math works

The calculator answers three teaching questions: (1) What G-stage is this eGFR today? (2) What was the average yearly change between two labs? (3) If that straight line continued, when would eGFR cross 30 or 15? Step 3 is the least clinically reliable but helps students understand why a −4.7 mL/min/1.73 m²/year slope feels “faster” than −2.

Sources & references

KDIGO 2024 CKD evaluation and management guidelineG and A staging, risk heatmap, monitoring frequency themes.
National Kidney Foundation — CKD patient educationPlain-language staging and when to see a nephrologist.
Peer-reviewed cohort literature on eGFR slope heterogeneityPopulation studies show wide variation—two-point linear extrapolation is not individual prognosis.

Estimate a single eGFR first with our GFR calculator, then return here when you have two comparable timed results.

Worked example

eGFR 52 → 45 over 18 months

Default demo — moderate decline on a straight line

Stage: G3a — eGFR 45–59

Annualized change: -4.67 mL/min/1.73 m² per year

Linear teaching horizons: ~3.2 years to eGFR 30, ~ 6.4 years to eGFR 15; eGFR in 5 years ≈ 21.7 if slope unchanged

Linear extrapolation is a teaching simplification. Your nephrology team uses trends, proteinuria, comorbidities, and shared decision-making—not a single projected date.

Frequently Asked Questions

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Nephrology & CKD education

Kidney Disease Progression Calculator

Last updated: June 4, 2026

Two-point slope or assumed annual eGFR loss

KDIGO-style G staging from current eGFR

Explicit limits: no ACR, no dialysis scheduling

Kidney disease progression

Linear eGFR slope from two labs or an assumed annual loss—education only, not dialysis planning.

Projection mode

Current eGFR (mL/min/1.73 m²)

Prior eGFR (older value)

Months between measurements

CKD stage (by current eGFR)

G3a

G3a — eGFR 45–59

Annualized eGFR change

-4.67 / year

Negative values mean average loss per year over the window you supplied (or the assumed slope).

Linear teaching projection (not a clinical date)

Rough years to 15 mL/min/1.73 m² if slope stayed constant: 6.4

Rough years to 30: 3.2

If the same straight line continued 5 years: eGFR ≈ 21.7

Linear extrapolation is a teaching simplification. Your nephrology team uses trends, proteinuria, comorbidities, and shared decision-making—not a single projected date.

KDIGO CKD heatmaps show wide individual trajectories; linear fit to two labs can mislead if one value was acute illness, dehydration, or medication change.
Albuminuria/creatinine ratio, blood pressure control, renin-angiotensin blockade (when appropriate), SGLT2 inhibitors in selected patients, and cause-specific care change slope—this page does not capture those levers.
Dialysis or transplant referral thresholds depend on symptoms, potassium, acid-base, volume overload, and nutrition—not eGFR alone.

Example projections (from calculator logic)

52 → 45 · 18 mo

-4.67 / yr

G3a · ~3.2 yr to 30 · ~6.4 yr to 15

72 → 68 · 24 mo

-2 / yr

G2 · slower decline

eGFR 38 · −3/yr assumed

~2.7 yr to 30

G3b · classroom-style input

35 → 22 · 12 mo

-13 / yr

G4 · ~0.5 yr to 15 if linear

CKD G-stage by eGFR (KDIGO — G category only)

Stage	eGFR (mL/min/1.73 m²)	Teaching meaning
G1	≥90	Normal or high; kidney damage may still exist (albuminuria, hematuria, imaging)
G2	60–89	Mildly decreased; monitor trend and cardiovascular risk
G3a	45–59	Mild to moderate decrease; many guidelines discuss nephrology co-management
G3b	30–44	Moderate to severe; medication dosing and complication screening intensify
G4	15–29	Severe; prepare for renal replacement therapy education when appropriate
G5	<15	Kidney failure range; dialysis/transplant decisions are clinical, not formula-based

Albuminuria (A) categories — needed for full KDIGO risk

This progression tool uses eGFR only. Ask your clinician for urine ACR on the same lab requisition as creatinine.

Category	Urine ACR	Progression context
A1 — Normal to mildly increased	<30 mg/g	Lower progression risk when eGFR stable
A2 — Moderately increased	30–300 mg/g	Moderate risk; ACEi/ARB and BP targets often emphasized
A3 — Severely increased	>300 mg/g	Higher progression and cardiovascular risk—needs specialist input

Interpreting annualized eGFR change (teaching bands)

Slope (approx.)	How teams often frame it
0 to −2 mL/min/1.73 m²/yr	Relatively slow in many cohorts—still monitor cause and albuminuria
−2 to −5	Common “moderate” decline range in teaching examples—therapy may bend curve
−5 to −10	Faster decline—often warrants expedited evaluation and adherence review
< −10	Rapid loss—exclude AKI on CKD, obstruction, relapse; urgent nephrology context

Annualized ΔeGFR = (eGFR_now − eGFR_prior) ÷ (months_between ÷ 12)

If ΔeGFR < 0 and current > target: years_to_target ≈ (current − target) ÷ |ΔeGFR|

Assumed-decline mode sets ΔeGFR = −(magnitude you enter) per year.

Common nephrology referral themes (simplified)

•eGFR <30 mL/min/1.73 m² (G4) or persistent rapid decline
•Urine ACR ≥300 mg/g (A3) or nephrotic-range proteinuria
•eGFR drop >25% within a year or unexplained hematuria
•Resistant hypertension, recurrent hyperkalemia, or refractory acidosis
•Known polycystic kidney disease, glomerulonephritis, or systemic disease affecting kidneys
•Pregnancy planning with moderate–advanced CKD

What this calculator does not model

•KDIGO combined G+A risk heatmap (requires urine albumin)
•Cystatin C–based eGFR or creatinine assay drift between labs
•Acute kidney injury recovery superimposed on CKD
•Competing mortality, transplant, or modality-specific survival models

How CKD progression math works

Sources & references

KDIGO 2024 CKD evaluation and management guidelineG and A staging, risk heatmap, monitoring frequency themes.
National Kidney Foundation — CKD patient educationPlain-language staging and when to see a nephrologist.
Peer-reviewed cohort literature on eGFR slope heterogeneityPopulation studies show wide variation—two-point linear extrapolation is not individual prognosis.

Estimate a single eGFR first with our GFR calculator, then return here when you have two comparable timed results.

Worked example

eGFR 52 → 45 over 18 months

Default demo — moderate decline on a straight line

Stage: G3a — eGFR 45–59

Annualized change: -4.67 mL/min/1.73 m² per year

Linear teaching horizons: ~3.2 years to eGFR 30, ~ 6.4 years to eGFR 15; eGFR in 5 years ≈ 21.7 if slope unchanged

Linear extrapolation is a teaching simplification. Your nephrology team uses trends, proteinuria, comorbidities, and shared decision-making—not a single projected date.