GFR Calculator: Glomerular Filtration Rate Calculation

What is Glomerular Filtration Rate (GFR)?

GFR is a key indicator of kidney function, reflecting the volume of blood filtration through the glomeruli per minute. To calculate, a GFR calculator is used, taking into account serum creatinine, age, gender, weight, and race.

GFR norms vary: for men - 90-120 ml/min/1.73m², for women - 85-110 ml/min/1.73m².

CKD-EPI Formula: Gold Standard

Calculating GFR using CKD-EPI is the most accurate method for adults:

GFR = 141 × min(Cr/κ, 1)^α × max(Cr/κ, 1)^-1.209 × 0.993^Age × [1.018 if female] × [1.159 if African American]

where κ = 0.7 (female) or 0.9 (male), α = -0.329 (female) or -0.411 (male).

Pros: High accuracy for GFR >60 ml/min.

Cons: Requires calibrated creatinine data.

Online CKD-EPI GFR calculator automates the calculation.

Cockcroft-Gault Formula

Adult GFR calculator based on creatinine uses the method:

GFR = (140 - Age) × Weight (kg) × [0.85 if female] / (72 × Cr)

Pros: Simplicity, does not require IFA.

Cons: Errors in obesity/cachexia.

Cockcroft-Gault GFR calculator is used for drug dose adjustments.

GFR Calculation in Children: Schwartz Formula

Schwartz GFR in children :

GFR = k × Height (cm) / Cr

where k=0.55 (children <1 year), 0.45 (adolescent girls), 0.7 (adolescent boys).

Pros: Child's height consideration.

Cons: Not validated for adults.

Child GFR calculator is available online.

GFR Grades and CKD Stages

Results of GFR calculation by calculator are interpreted according to KDIGO classification (2013):

CKD Stage	Description	GFR Level (ml/min/1.73m²)
1	Kidney damage with normal GFR	≥90
2	Mild decrease in GFR	60–89
3a	Moderate decrease in GFR	45–59
3b	Significant decrease in GFR	30–44
4	Severe decrease in GFR	15–29
5	Kidney failure	<15

CKD GFR calculator automatically determines the CKD stage. Values <60 ml/min/1.73m² for >3 months are criteria for CKD.

GFR Norms and Limitations

GFR norm in women: 85-110 ml/min.
GFR norm in men: 90-120 ml/min.

Limitations:

Pregnancy
Extreme muscle mass values
Acute kidney failure

Online creatinine GFR calculator does not replace comprehensive diagnostics!

Practical Use

Universal GFR calculator integrates CKD-EPI, Cockcroft-Gault formulas. For online GFR calculator calculation, creatinine (µmol/l), age, gender, height/weight are required.