eGFR to CrCl Calculator (GFR to Creatinine Clearance)

Convert eGFR to creatinine clearance in mL/min using height and weight, estimate Cockcroft-Gault CrCl, or convert CrCl back to eGFR per 1.73 m².

References / Guidelines (for further reading)

National Kidney Foundation (NKF): eGFR and kidney function overview pages.
KDIGO: chronic kidney disease guideline overview materials.
NIDDK: Determining Drug Dosing in Adults with Chronic Kidney Disease.
Medication labeling (FDA/your country’s regulator): renal dosing sections often specify whether to use Cockcroft–Gault CrCl vs eGFR.

Medical disclaimer: Educational use only; not medical advice. Do not use these estimates to start/stop/change medicines or to make diagnosis/dosing decisions—follow medication labeling and consult a clinician/pharmacist. The Absolute GFR mode is a BSA scaling conversion (not a measured urine creatinine clearance). The Cockcroft–Gault mode is intended for adults with stable kidney function and may be unreliable in rapidly changing creatinine/AKI, pregnancy, dialysis, pediatrics, amputations, edema, or very low/high muscle mass/extreme body size. Some medication labels use Cockcroft–Gault CrCl. Current NKF guidance supports transitioning to BSA-adjusted race-free eGFR for adult medication decisions; confirm the appropriate equation, weight method and medication-specific guidance with a clinician or pharmacist.

Last reviewed: 2026-01-01

Indexed GFR To Absolute (Unindexed) GFR Formula

The following formula is used to convert a BSA-indexed GFR (mL/min/1.73m²) into an absolute (unindexed) GFR (mL/min) using the patient’s body surface area (BSA). This conversion is not the same as a measured urine creatinine clearance.

GFR absolute = (GFR indexed \times BSA) / 1.73

Variables:

GFR_absolute is the absolute (unindexed) GFR (mL/min)
GFR_indexed is the BSA-indexed GFR (mL/min/1.73m²)
BSA is the body surface area (m²)

To calculate the absolute (unindexed) GFR, multiply the indexed GFR by the body surface area, then divide by 1.73 (the standard BSA used for indexing).

Indexed GFR to Absolute (Unindexed) GFR Conversion Table (GFR_absolute = GFR_indexed × BSA / 1.73)
GFR (mL/min/1.73m²)	Absolute GFR at BSA 1.50 m² (mL/min)	Absolute GFR at BSA 1.73 m² (mL/min)	Absolute GFR at BSA 2.00 m² (mL/min)
15	13.0	15	17.3
20	17.3	20	23.1
25	21.7	25	28.9
30	26.0	30	34.7
35	30.3	35	40.5
40	34.7	40	46.2
45	39.0	45	52.0
50	43.4	50	57.8
55	47.7	55	63.6
60	52.0	60	69.4
65	56.4	65	75.1
70	60.7	70	80.9
75	65.0	75	86.7
80	69.4	80	92.5
85	73.7	85	98.3
90	78.0	90	104.0
95	82.4	95	109.8
100	86.7	100	115.6
110	95.4	110	127.2
120	104.0	120	138.7
Formula: Absolute GFR (mL/min) = Indexed GFR (mL/min/1.73m²) × (BSA (m²) / 1.73). Values rounded to one decimal place.

What Is Indexed GFR vs. Creatinine Clearance?

GFR (glomerular filtration rate) describes how much fluid the kidneys filter per unit time. Many lab-reported eGFR values are indexed to a standard body surface area of 1.73 m² (reported as mL/min/1.73m²) so results can be compared across people of different sizes.

Creatinine clearance (CrCl) is different: it is typically measured from urine collection (e.g., 24-hour urine) or estimated from serum creatinine using formulas such as Cockcroft–Gault. CrCl and GFR are related but not interchangeable; CrCl often overestimates true GFR due to creatinine tubular secretion.

How to Convert Indexed GFR to Absolute (Unindexed) GFR

The following steps outline how to convert a BSA-indexed GFR to an absolute (unindexed) GFR.

Determine the indexed GFR in mL/min/1.73m².
Determine the patient’s BSA in m².
Use the formula from above: Absolute GFR = (Indexed GFR × BSA) / 1.73.
Calculate the absolute (unindexed) GFR in mL/min.
Check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Indexed GFR = 80 mL/min/1.73m²

BSA = 1.8 m²

Absolute (unindexed) GFR = (80 × 1.8) / 1.73 = 83.24 mL/min (≈ 83.2 mL/min)