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Enter your most recent eGFR, then either an older eGFR with the number of months between labs or switch to assumed annual decline mode for a classroom-style straight-line projection. The tool shows KDIGO-style G-stage by current eGFR, an annualized change, and rough years to 15 or 30 if the slope is downward—always with the caveat that real trajectories bend and therapies change slope.
Last updated: April 20, 2026
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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.
Staging by eGFR alone is incomplete without albuminuria class—but matches common introductory teaching charts.
Two-point mode divides the difference between labs by months converted to years to get an average annualized slope.
If slope is negative and current eGFR is above the target, the page solves for crossing times in a purely linear model.
If eGFR fell from 52 to 45 over 18 months, the average slope is about −4.7 mL/min/1.73 m² per year—then a naïve straight line crosses 30 in roughly 3.2 years and 15 in roughly 6.4 years if nothing changed (which is rarely true clinically).
Annualized change = (eGFR_now − eGFR_prior) ÷ (months ÷ 12). If that value is negative, the calculator treats −slope as positive speed toward lower numbers and divides the gap to a target (for example 15) by that speed to get a teaching year estimate.
First estimate eGFR with our GFR calculator, then revisit slope here when you have two timed values.
Get a Custom Calculator for Your PlatformStage G3a with annualized change about -4.67 mL/min/1.73 m² per year produces the horizon lines shown in the card—use them only to understand slope arithmetic, not to plan life events.
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