Filtration Rate Calculator

The kidneys filter waste from the blood, and measuring their filtration rate is a key way to assess kidney health and detect disease. The Filtration Rate Calculator supports two modes: select Glomerular Filtration Rate (GFR) and enter your age, gender, weight, height, and serum creatinine (plus optional Cystatin C) to get your GFR, CKD Stage, and Kidney Function %. Select Ultrafiltration Rate (UFR) and enter your fluid to remove and treatment duration to calculate your UFR and its safety status. Also try the find Vapor Fraction with Flash Calculation Calculator.

years

Gender *

kg
cm
mg/dL

Normal range: 0.6-1.2 mg/dL

mg/L

Optional - for more accurate GFR calculation

liters

For ultrafiltration rate calculation

hours

For ultrafiltration rate calculation

Results

Primary Result

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CKD Stage

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Kidney Function

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UFR Safety Status

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Frequently Asked Questions

What is a normal GFR value?

A normal GFR is 90 mL/min/1.73m² or higher. GFR values between 60-89 may be normal for some people, especially older adults. Values below 60 for three months or more indicate chronic kidney disease. See also our CSTR Design.

What do the different CKD stages mean?

Stage 1 (GFR ≥90): Normal or high with kidney damage. Stage 2 (GFR 60-89): Mild decrease with kidney damage. Stage 3 (GFR 30-59): Moderate decrease. Stage 4 (GFR 15-29): Severe decrease. Stage 5 (GFR <15): Kidney failure.

What is ultrafiltration rate (UFR)?

UFR measures how quickly fluid is removed during dialysis, expressed as mL/kg/hour. A safe UFR is generally less than 10-13 mL/kg/hour to reduce cardiovascular stress and improve treatment tolerance.

How accurate is the CKD-EPI equation?

The CKD-EPI equation is currently the most accurate method for estimating GFR in adults. The 2021 race-free version eliminates racial bias while maintaining clinical accuracy for kidney function assessment. You might also find our Heat Exchanger Calculator useful.

When should cystatin C be used?

Cystatin C provides a more accurate GFR estimate when creatinine may be unreliable, such as in patients with unusual muscle mass, vegetarian diets, or when more precision is needed for clinical decisions.

Can medications affect creatinine levels?

Yes, certain medications can increase serum creatinine without affecting actual kidney function, including ACE inhibitors, ARBs, and some antibiotics. Always consult your healthcare provider about medication effects.

What factors influence safe fluid removal rates?

Safe UFR depends on treatment time, patient size, cardiovascular health, and fluid distribution. Longer treatment times and good heart function allow for higher safe removal rates.

How often should GFR be monitored?

Monitoring frequency depends on CKD stage and risk factors. Generally, stages 1-2 require annual monitoring, stage 3 every 6-12 months, and stages 4-5 every 3-6 months or more frequently.