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eGFR and creatinine clearance calculator

CKD-EPI eGFR and Cockcroft–Gault creatinine clearance for drug dosing, using creatinine in mg/dL.

What this calculator is for

It gives two different estimates of kidney function from a serum creatinine in mg/dL, the unit most Pakistani labs use.

  • eGFR (CKD-EPI 2021) stages chronic kidney disease. It is reported per 1.73 m² of body surface area and does not use weight or race.
  • Creatinine clearance (Cockcroft–Gault) is what many manufacturers use for dose adjustment, including several antibiotics and the direct oral anticoagulants.

The formulas

Cockcroft–Gault: CrCl (mL/min) = (140 − age) × weight (kg) ÷ (72 × creatinine in mg/dL), multiplied by 0.85 for women. CKD-EPI 2021 is more complex and is calculated for you. To convert creatinine from µmol/L to mg/dL, divide by 88.4.

Interpreting eGFR (CKD stages)

  • G1: 90 or more (with other evidence of kidney damage)
  • G2: 60–89
  • G3a: 45–59; G3b: 30–44
  • G4: 15–29
  • G5: below 15 (kidney failure)

CKD needs abnormal results for more than 3 months, and staging also includes urine albumin-to-creatinine ratio.

Worked example

A 70-year-old woman weighing 55 kg with creatinine 1.2 mg/dL: eGFR is about 49 (G3a), but creatinine clearance is about 38 mL/min. For a drug whose dose changes below 50 mL/min, the two numbers lead to different doses. Use the one the product information specifies.

Limitations and pitfalls

  • Neither is valid in acute kidney injury, when creatinine is changing day to day. Use the trend and the urine output instead.
  • Creatinine depends on muscle mass. Both overestimate function in frail, elderly, malnourished and amputee patients, and underestimate it in very muscular people.
  • Cockcroft–Gault with actual weight overestimates clearance in obesity; many units use ideal or adjusted body weight.
  • Not valid in pregnancy or in children; children need a paediatric formula.
  • A "normal" creatinine of 1.0 mg/dL in a small elderly woman can hide significant impairment.

See acute kidney injury, low urine output, high potassium, apixaban, vancomycin and the textbook chapter on GFR and renal clearance.

Frequently asked questions

What is the difference between eGFR and creatinine clearance?

eGFR (CKD-EPI) is used to stage chronic kidney disease and is normalised to body surface area. Creatinine clearance (Cockcroft–Gault) uses weight and is what many drug manufacturers use for dose adjustment.

How do I convert creatinine from µmol/L to mg/dL?

Divide by 88.4. For example 106 µmol/L is about 1.2 mg/dL.

Can I use eGFR in acute kidney injury?

No. eGFR assumes a stable creatinine. In AKI, follow the trend in creatinine and urine output instead.

Which weight should I use in the Cockcroft–Gault formula?

Actual body weight in most patients. In obesity, actual weight overestimates clearance, so many units use ideal or adjusted body weight; check your local policy.

A calculator supports, but does not replace, clinical judgement. Check results before acting on them.