𧬠Carboplatin Dose Calculator
Calvert formula: dose = AUC x (GFR + 25). Educational only.
GFR ideally measured (e.g., nuclear medicine) or estimated. Our creatinine clearance calculator estimates it via Cockcroft-Gault.
EDUCATIONAL ONLY. Chemotherapy dosing must be calculated and verified by the oncology team and pharmacist.
Carboplatin is dosed unlike almost every other chemotherapy drug: not by body surface area, but by kidney function. The Calvert formula, published in 1989, sets the dose from a target AUC (drug exposure) and the patient's GFR: dose = AUC x (GFR + 25). This calculator runs that formula. It exists for education: real carboplatin dosing is calculated and double-checked by the oncology team and pharmacist, never from a webpage.
How to Use This Calculator
Select the target AUC from the treatment protocol and enter the GFR. The milligram dose appears.
Pick the target AUC the protocol specifies: commonly 5 or 6 for most solid tumors, sometimes 4 or 7.
Enter GFR in mL/min, ideally measured. Estimated creatinine clearance from our CrCl calculator is the common substitute.
Read the dose. Note the capping warning if GFR exceeds 125: most protocols cap the dose, and the protocol always wins.
The Calvert Formula
Calvert and colleagues showed that carboplatin clearance is essentially renal clearance plus a constant 25 mL/min of non-renal clearance, and that toxicity (especially thrombocytopenia) tracks the area under the concentration-time curve. So instead of dosing by size and hoping exposure lands right, the formula targets exposure directly: pick the AUC the cancer needs, multiply by the patient's total clearance, and the dose follows. It was a genuine advance in precision dosing, and it remains the standard three decades later.
The GFR input deserves care. Measured GFR (nuclear medicine, iothalamate) is the gold standard but rarely available; estimated CrCl via Cockcroft-Gault is the workhorse substitute. Serum creatinine methods matter too: the IDMS-traceable assays read lower than older methods, which inflates estimated GFR, one reason many centers cap the GFR used in the formula at 125 mL/min. When in doubt, the pharmacist recalculates with the institution's preferred method.
Worked Example
Target AUC 5, GFR 75 mL/min. Dose = 5 x (75 + 25) = 500 mg. At AUC 6 with the same kidneys: 6 x 100 = 600 mg. Now a patient with GFR 140: the raw formula gives 5 x 165 = 825 mg, but most protocols cap GFR at 125, giving 5 x 150 = 750 mg, because estimated GFR above 125 is unreliable and the uncapped dose risks overdosing. The cap exists to protect patients from the formula's own optimism at the top end.
Why AUC Instead of Body Surface Area
Most chemotherapy is dosed per square meter of body surface area, which predicts drug handling crudely. Carboplatin is special because the kidney does almost all the work of clearing it, so kidney function predicts exposure far better than size does. Two patients with the same BSA but GFRs of 60 and 120 need very different doses: the BSA approach would give them the same milligrams and produce wildly different exposures and toxicities. Calvert fixed that by making the kidney the dose dial. It is the cleanest example in oncology of dosing the exposure rather than the patient.
For patients and families, the practical takeaway is reassurance about dose changes: if the oncologist lowers the carboplatin dose after seeing new kidney labs, that is the formula working as designed, not a mistake or a weaker treatment. Kidney function fluctuates with hydration, medications, and age, and the dose follows it. Every dose gets independently verified by pharmacy before it reaches the infusion chair, which is exactly as it should be.
Safety Notes That Matter
Carboplatin's dose-limiting toxicity is myelosuppression, especially thrombocytopenia (low platelets), which is why the AUC target balances cancer kill against marrow tolerance. Allergic reactions become more common after multiple cycles. Kidney function gets rechecked before every cycle because the dose depends on it. This page shows the arithmetic behind those decisions so patients can follow the conversation; it does not participate in the decisions. If you are a student, verify every number against your institution's protocol: real practice has local rules on GFR capping, creatinine assay correction, and AUC selection that supersede any calculator.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What is the Calvert formula?
Dose (mg) = target AUC x (GFR + 25), published by Calvert et al. in 1989. It doses carboplatin by kidney function and target drug exposure rather than body surface area, because the kidneys clear almost all carboplatin. It remains the standard method.
How do you calculate carboplatin dose?
Multiply the protocol's target AUC (commonly 5 or 6) by the patient's GFR plus 25. Example: AUC 5 with GFR 75 gives 5 x 100 = 500 mg. Many protocols cap the GFR used at 125 mL/min. Oncology pharmacists verify every dose.
What is AUC in carboplatin dosing?
Area under the plasma concentration-time curve, a measure of total drug exposure in mg/mL/min. Higher AUC means more cancer kill and more toxicity, especially low platelets. Protocols select the AUC; the Calvert formula converts it to milligrams for the individual patient.
Why is carboplatin dosed by GFR instead of weight?
Because renal clearance dominates carboplatin elimination, kidney function predicts drug exposure far better than body size. Two same-sized patients with different kidney function need different doses, which BSA dosing would miss entirely.
What GFR is used in the Calvert formula?
Ideally a measured GFR; in practice, estimated creatinine clearance via Cockcroft-Gault is the common substitute. Many centers cap the value at 125 mL/min because creatinine-based estimates overread at the top end. Institutional protocol governs the details.
What happens if carboplatin dose is too high?
Dose-limiting toxicity is myelosuppression, particularly thrombocytopenia (dangerously low platelets), plus nausea, kidney injury, and with repeated cycles, allergic reactions. This is why exposure-targeted dosing and pharmacist verification exist.
Can carboplatin dose be reduced?
Yes, oncologists adjust AUC targets and doses for low kidney function, frailty, low blood counts, or prior toxicity. Dose reductions following the formula's logic are standard practice, not a sign of weaker treatment.
How often is kidney function checked during carboplatin treatment?
Before every cycle, at minimum, since the dose depends on it. Creatinine can shift with hydration, medications, and illness, and the dose follows the labs.
What is the maximum carboplatin dose?
There is no universal maximum; it follows AUC x (GFR+25) with protocol-specific GFR caps (commonly 125 mL/min, giving 750 mg at AUC 5). Some protocols set absolute caps. The treatment protocol and pharmacist have the final word.
Is this calculator safe to use for real dosing?
No. It is educational. Real carboplatin dosing requires the treatment protocol, verified kidney function, pharmacist double-check, and oncology supervision. Never dose chemotherapy from a webpage.