Creatinine Clearance Calculator (Cockcroft-Gault)
Use this creatinine clearance calculator to estimate your kidney function using the Cockcroft-Gault equation.
Updated September 18, 2026
Calculated instantly in your browser — nothing is sent to or stored on our servers.
Medical Disclaimer: This calculator provides a general estimate based on established research and is for educational purposes only, not a substitute for medical advice. Individual results can vary based on health conditions, so consult a qualified healthcare professional or registered dietitian before making significant changes to your diet, exercise, or health routine. Read our full Medical Disclaimer.
How Creatinine Clearance Is Calculated
Cockcroft-Gault was published in 1976 as a practical way to estimate kidney function from routine labs, without needing a timed urine collection. It remains in wide use nearly 50 years later for one specific reason: much of the drug dosing literature, package inserts, and clinical guidance in use today was calibrated against this exact formula, not a newer one¹.
What This Calculator Measures
This estimates creatinine clearance in mL/min from age, sex, weight, and serum creatinine, with a choice of which weight basis to use, since the formula wasn't derived from a population with a wide obesity range.
The Formula
Creatinine Clearance (mL/min) = [(140 − Age) × Weight (kg)] ÷ (72 × Serum Creatinine [mg/dL])
Multiplied by 0.85 for women.
How This Calculator Computes Your Result
Enter age, sex, weight, and serum creatinine. Choose which weight to use, actual, ideal, or adjusted body weight, since Cockcroft-Gault can meaningfully overestimate clearance in obesity if actual weight is used uncritically. This calculator makes that choice explicit rather than silently defaulting to actual weight for everyone, reusing the same Devine ideal-body-weight and 0.4 adjustment-factor formulas already established on this site's calculators for ideal weight and adjusted body weight.
Why the Choice of Formula Genuinely Matters, Not Just as a Technicality
Cockcroft-Gault and the newer CKD-EPI equation don't just differ slightly, they diverge in predictable, clinically meaningful directions. Research comparing the formulas found Cockcroft-Gault results run progressively lower than CKD-EPI as patients get older, and progressively higher than CKD-EPI as weight increases, in other words, the two formulas don't just disagree randomly, they disagree in opposite directions depending on the patient²
This isn't a minor academic distinction. A study of atrial fibrillation patients on the blood thinner dabigatran found that when dosing decisions were based on Cockcroft-Gault versus the newer CKD-EPI method, patients given a high dose based on Cockcroft-Gault had more than double the risk of a hemorrhagic event compared with those given a normal dose (hazard ratio 2.32)³. Which formula a clinician uses is a real decision with real downstream consequences, not an interchangeable technical detail.
A Note on Accuracy
Cockcroft-Gault was derived from a specific historical population and is known to be less accurate in extremes of body weight, the elderly, and in those with rapidly changing kidney function. It was not designed for and should not be used in acute kidney injury. This estimates kidney function, it does not diagnose any condition, and should never be used to adjust an actual medication dose without a clinician's involvement.
Frequently Asked Questions
How is this different from eGFR?
eGFR (CKD-EPI) is a separate, methodologically different kidney function estimate, and is now generally preferred for kidney function staging in most clinical contexts. Cockcroft-Gault remains relevant primarily because many existing drug dosing guidelines were calibrated to it specifically, and the two formulas diverge in predictable directions with age and body weight², they're related but not interchangeable.
Why does this ask which weight to use?
Cockcroft-Gault was derived from a population without a wide obesity range. Some clinical contexts use ideal or adjusted body weight instead of actual weight for obese patients, this substitution matters, so the tool makes the choice explicit rather than silently defaulting to actual weight for everyone.
Does the choice of formula actually affect real outcomes?
Yes, demonstrably. A study of patients on a commonly prescribed blood thinner found that dosing based on Cockcroft-Gault versus a newer formula led to more than double the risk of a serious bleeding event when a high dose was given based on the Cockcroft-Gault result³. Formula choice is a genuine clinical decision, not a technicality.
Can I use this number to adjust my own medication dose?
No. This estimates kidney function, it does not diagnose any condition, and should never be used to adjust an actual medication dose without a clinician's involvement.
Sources
Prediction of Creatinine Clearance from Serum Creatinine, Cockcroft & Gault, Nephron, 1976
Performance of the Cockcroft-Gault, MDRD, and New CKD-EPI Formulas in Relation to GFR, Age, and Body Size, Michels et al., Clinical Journal of the American Society of Nephrology, 2010, verify exact author list before publishing
Choice of Renal Function Estimator Influences Adverse Outcomes with Dabigatran Etexilate in Patients with Atrial Fibrillation, Study on real-world clinical consequences of formula choice in anticoagulant dosing
Creatinine Clearance Calculator (Cockcroft-Gault)
Use this creatinine clearance calculator to estimate your kidney function using the Cockcroft-Gault equation.
Updated September 18, 2026
Calculated instantly in your browser — nothing is sent to or stored on our servers.
Medical Disclaimer: This calculator provides a general estimate based on established research and is for educational purposes only, not a substitute for medical advice. Individual results can vary based on health conditions, so consult a qualified healthcare professional or registered dietitian before making significant changes to your diet, exercise, or health routine. Read our full Medical Disclaimer.
How Creatinine Clearance Is Calculated
Cockcroft-Gault was published in 1976 as a practical way to estimate kidney function from routine labs, without needing a timed urine collection. It remains in wide use nearly 50 years later for one specific reason: much of the drug dosing literature, package inserts, and clinical guidance in use today was calibrated against this exact formula, not a newer one¹.
What This Calculator Measures
This estimates creatinine clearance in mL/min from age, sex, weight, and serum creatinine, with a choice of which weight basis to use, since the formula wasn't derived from a population with a wide obesity range.
The Formula
Creatinine Clearance (mL/min) = [(140 − Age) × Weight (kg)] ÷ (72 × Serum Creatinine [mg/dL])
Multiplied by 0.85 for women.
How This Calculator Computes Your Result
Enter age, sex, weight, and serum creatinine. Choose which weight to use, actual, ideal, or adjusted body weight, since Cockcroft-Gault can meaningfully overestimate clearance in obesity if actual weight is used uncritically. This calculator makes that choice explicit rather than silently defaulting to actual weight for everyone, reusing the same Devine ideal-body-weight and 0.4 adjustment-factor formulas already established on this site's calculators for ideal weight and adjusted body weight.
Why the Choice of Formula Genuinely Matters, Not Just as a Technicality
Cockcroft-Gault and the newer CKD-EPI equation don't just differ slightly, they diverge in predictable, clinically meaningful directions. Research comparing the formulas found Cockcroft-Gault results run progressively lower than CKD-EPI as patients get older, and progressively higher than CKD-EPI as weight increases, in other words, the two formulas don't just disagree randomly, they disagree in opposite directions depending on the patient²
This isn't a minor academic distinction. A study of atrial fibrillation patients on the blood thinner dabigatran found that when dosing decisions were based on Cockcroft-Gault versus the newer CKD-EPI method, patients given a high dose based on Cockcroft-Gault had more than double the risk of a hemorrhagic event compared with those given a normal dose (hazard ratio 2.32)³. Which formula a clinician uses is a real decision with real downstream consequences, not an interchangeable technical detail.
A Note on Accuracy
Cockcroft-Gault was derived from a specific historical population and is known to be less accurate in extremes of body weight, the elderly, and in those with rapidly changing kidney function. It was not designed for and should not be used in acute kidney injury. This estimates kidney function, it does not diagnose any condition, and should never be used to adjust an actual medication dose without a clinician's involvement.
Frequently Asked Questions
How is this different from eGFR?
eGFR (CKD-EPI) is a separate, methodologically different kidney function estimate, and is now generally preferred for kidney function staging in most clinical contexts. Cockcroft-Gault remains relevant primarily because many existing drug dosing guidelines were calibrated to it specifically, and the two formulas diverge in predictable directions with age and body weight², they're related but not interchangeable.
Why does this ask which weight to use?
Cockcroft-Gault was derived from a population without a wide obesity range. Some clinical contexts use ideal or adjusted body weight instead of actual weight for obese patients, this substitution matters, so the tool makes the choice explicit rather than silently defaulting to actual weight for everyone.
Does the choice of formula actually affect real outcomes?
Yes, demonstrably. A study of patients on a commonly prescribed blood thinner found that dosing based on Cockcroft-Gault versus a newer formula led to more than double the risk of a serious bleeding event when a high dose was given based on the Cockcroft-Gault result³. Formula choice is a genuine clinical decision, not a technicality.
Can I use this number to adjust my own medication dose?
No. This estimates kidney function, it does not diagnose any condition, and should never be used to adjust an actual medication dose without a clinician's involvement.
Sources
Prediction of Creatinine Clearance from Serum Creatinine, Cockcroft & Gault, Nephron, 1976
Performance of the Cockcroft-Gault, MDRD, and New CKD-EPI Formulas in Relation to GFR, Age, and Body Size, Michels et al., Clinical Journal of the American Society of Nephrology, 2010, verify exact author list before publishing
Choice of Renal Function Estimator Influences Adverse Outcomes with Dabigatran Etexilate in Patients with Atrial Fibrillation, Study on real-world clinical consequences of formula choice in anticoagulant dosing
Creatinine Clearance Calculator (Cockcroft-Gault)
Use this creatinine clearance calculator to estimate your kidney function using the Cockcroft-Gault equation.
Updated September 18, 2026
Calculated instantly in your browser — nothing is sent to or stored on our servers.
Medical Disclaimer: This calculator provides a general estimate based on established research and is for educational purposes only, not a substitute for medical advice. Individual results can vary based on health conditions, so consult a qualified healthcare professional or registered dietitian before making significant changes to your diet, exercise, or health routine. Read our full Medical Disclaimer.
How Creatinine Clearance Is Calculated
Cockcroft-Gault was published in 1976 as a practical way to estimate kidney function from routine labs, without needing a timed urine collection. It remains in wide use nearly 50 years later for one specific reason: much of the drug dosing literature, package inserts, and clinical guidance in use today was calibrated against this exact formula, not a newer one¹.
What This Calculator Measures
This estimates creatinine clearance in mL/min from age, sex, weight, and serum creatinine, with a choice of which weight basis to use, since the formula wasn't derived from a population with a wide obesity range.
The Formula
Creatinine Clearance (mL/min) = [(140 − Age) × Weight (kg)] ÷ (72 × Serum Creatinine [mg/dL])
Multiplied by 0.85 for women.
How This Calculator Computes Your Result
Enter age, sex, weight, and serum creatinine. Choose which weight to use, actual, ideal, or adjusted body weight, since Cockcroft-Gault can meaningfully overestimate clearance in obesity if actual weight is used uncritically. This calculator makes that choice explicit rather than silently defaulting to actual weight for everyone, reusing the same Devine ideal-body-weight and 0.4 adjustment-factor formulas already established on this site's calculators for ideal weight and adjusted body weight.
Why the Choice of Formula Genuinely Matters, Not Just as a Technicality
Cockcroft-Gault and the newer CKD-EPI equation don't just differ slightly, they diverge in predictable, clinically meaningful directions. Research comparing the formulas found Cockcroft-Gault results run progressively lower than CKD-EPI as patients get older, and progressively higher than CKD-EPI as weight increases, in other words, the two formulas don't just disagree randomly, they disagree in opposite directions depending on the patient²
This isn't a minor academic distinction. A study of atrial fibrillation patients on the blood thinner dabigatran found that when dosing decisions were based on Cockcroft-Gault versus the newer CKD-EPI method, patients given a high dose based on Cockcroft-Gault had more than double the risk of a hemorrhagic event compared with those given a normal dose (hazard ratio 2.32)³. Which formula a clinician uses is a real decision with real downstream consequences, not an interchangeable technical detail.
A Note on Accuracy
Cockcroft-Gault was derived from a specific historical population and is known to be less accurate in extremes of body weight, the elderly, and in those with rapidly changing kidney function. It was not designed for and should not be used in acute kidney injury. This estimates kidney function, it does not diagnose any condition, and should never be used to adjust an actual medication dose without a clinician's involvement.
Frequently Asked Questions
How is this different from eGFR?
eGFR (CKD-EPI) is a separate, methodologically different kidney function estimate, and is now generally preferred for kidney function staging in most clinical contexts. Cockcroft-Gault remains relevant primarily because many existing drug dosing guidelines were calibrated to it specifically, and the two formulas diverge in predictable directions with age and body weight², they're related but not interchangeable.
Why does this ask which weight to use?
Cockcroft-Gault was derived from a population without a wide obesity range. Some clinical contexts use ideal or adjusted body weight instead of actual weight for obese patients, this substitution matters, so the tool makes the choice explicit rather than silently defaulting to actual weight for everyone.
Does the choice of formula actually affect real outcomes?
Yes, demonstrably. A study of patients on a commonly prescribed blood thinner found that dosing based on Cockcroft-Gault versus a newer formula led to more than double the risk of a serious bleeding event when a high dose was given based on the Cockcroft-Gault result³. Formula choice is a genuine clinical decision, not a technicality.
Can I use this number to adjust my own medication dose?
No. This estimates kidney function, it does not diagnose any condition, and should never be used to adjust an actual medication dose without a clinician's involvement.
Sources
Prediction of Creatinine Clearance from Serum Creatinine, Cockcroft & Gault, Nephron, 1976
Performance of the Cockcroft-Gault, MDRD, and New CKD-EPI Formulas in Relation to GFR, Age, and Body Size, Michels et al., Clinical Journal of the American Society of Nephrology, 2010, verify exact author list before publishing
Choice of Renal Function Estimator Influences Adverse Outcomes with Dabigatran Etexilate in Patients with Atrial Fibrillation, Study on real-world clinical consequences of formula choice in anticoagulant dosing