What is the Calvert formula?

The Calvert formula sets carboplatin dose in milligrams equal to the target AUC multiplied by the sum of GFR and 25. The added 25 represents non-renal clearance. Because carboplatin is almost entirely renally cleared, dosing to a target exposure gives more consistent results than body surface area dosing.

Why cap the GFR at 125 mL/min?

After creatinine assays were standardised, estimated GFR can read higher than the true value, which would overdose carboplatin and increase toxicity. Regulators advise capping the GFR used in the Calvert formula at about 125 mL/min, and this tool applies that cap by default.

Should I use measured or estimated GFR?

A measured GFR, for example by EDTA or iohexol clearance, is most accurate and preferred where available. Where it is not, Cockcroft-Gault creatinine clearance is the conventional estimate used in many carboplatin protocols. Follow whichever your regimen specifies.

Is the result a total dose or per square metre?

It is a total milligram dose for the patient, not a dose per square metre of body surface area. That is a defining feature of AUC dosing and a common source of error, so double-check that prescriptions are written as a total dose.

Does this replace a pharmacist or protocol check?

No. Carboplatin is a high-risk chemotherapy agent. This tool reproduces the formula but cannot verify the indication, the AUC target, organ function, or prior toxicity. Every dose must be confirmed against the protocol and independently checked before administration.

Carboplatin AUC Dose Calculator (Calvert Formula)

Carboplatin is dosed to a target area under the concentration-time curve rather than to body surface area, because its clearance is almost entirely renal and tracks kidney function closely. The Calvert formula converts a target AUC and the patient’s GFR into a single total milligram dose.

How it works

The core formula is short, but the GFR it uses matters enormously:

dose (mg) = target AUC x (GFR + 25)

If a measured GFR is not available, the tool estimates creatinine clearance with Cockcroft-Gault:

CrCl = [(140 - age) x weight(kg) x (0.85 if female)] / (72 x Scr_mg/dL)

Creatinine entered in micromoles per litre is converted to mg/dL by dividing by 88.42 before the estimate.

The GFR cap and an example

Because standardised creatinine assays can make estimated GFR read higher than the truth, dosing on an uncapped high estimate risks carboplatin overdose and severe myelosuppression. For that reason the tool caps the GFR used in the formula at 125 mL/min by default. As an example, a target AUC of 5 with a GFR of 90 mL/min gives a dose of 5 x (90 + 25) which is 575 mg total. Always confirm the GFR method, the AUC target, and the final dose against your chemotherapy protocol, and have it independently checked before it reaches the patient.