Convert a prescribed single dose in mg/m² to mg, normalize a known mg dose by body surface area, or estimate BSA. These are arithmetic tools: a clinician or pharmacist must verify the prescription, protocol, BSA method and any adjustments.

Multiply a prescribed dose per area by the BSA used for that administration.

Arithmetic only. Use clinician-prescribed values and the required protocol. This tool does not choose a drug, dose, BSA cap, schedule or patient-specific adjustment. Confirm calculations with a qualified clinician or pharmacist before use.

Prescribed options and display

Blank means no cap. Enter a cap only when the applicable clinical protocol requires it.

Blank omits the course total. This multiplies identical doses; it does not determine a schedule.

mg/m² Dose Formula

To normalize a known dose M in mg to mg/m², divide it by the BSA used for the calculation. With the Mosteller estimate, BSA = √(W × H / 3600), where W is in kg and H in cm:

D = (M) / (√((W H) / (3600)))

Variables:

  • D is the dose in mg/m2
  • M is the medication dosage in mg
  • W is the weight of the patient in kg
  • H is the height of the patient in cm

To calculate dose per area, first estimate BSA = √(W × H / 3600), then calculate D = M ÷ BSA. Conversely, a prescribed dose per area in mg/m² multiplied by the BSA used in m² gives the single dose in mg. Use a direct BSA, another equation or a BSA cap only when the applicable clinical protocol specifies it.

What is a mg/m² Dose?

A dose expressed in mg/m² is an amount of medication per unit body surface area. Some treatment protocols use it as one input to dosing. A BSA estimate does not by itself establish a safe or effective dose: the prescribed drug, clinical protocol, organ function, toxicity, treatment timing and other patient factors can change the dose. The calculator does not select or validate those decisions.

How to Calculate mg/m² Dose?

The following steps outline how to calculate the mg/m² Dose using the given formula:

  1. First, determine the medication dosage (M) in mg.
  2. Next, determine the weight of the patient (W) in kg.
  3. Next, determine the height of the patient (H) in cm.
  4. Next, calculate BSA = √(W × H / 3600), then use D = M ÷ BSA to obtain the dose per area in mg/m².
  5. Finally, calculate the mg/m² Dose.
  6. After inserting the variables and calculating the result, check your answer with a calculator.

Example Problem:

Use the following variables as an example problem to test your knowledge:

Medication dosage (M) = 50 mg

Weight of the patient (W) = 60 kg

Height of the patient (H) = 170 cm

For this arithmetic example, Mosteller BSA = √(60 × 170 / 3600) ≈ 1.683250823 m². A known single dose of 50 mg therefore corresponds to 50 ÷ 1.683250823 ≈ 29.70 mg/m². This is not a recommended prescription. The equation uses full precision before display rounding.

Formula references: Mosteller, Haycock, Gehan and George, and the published comparison of BSA equations. No BSA cap or course schedule is selected automatically. A count of equal doses only multiplies the same calculated single dose.