What is the Mosteller formula?

Mosteller (1987): BSA (m²) = √[(height in cm × weight in kg) / 3600]. It is the most widely used formula in pediatric oncology and clinical practice because it is simple and accurate across a broad age range.

What is the DuBois formula?

DuBois & DuBois (1916): BSA (m²) = 0.007184 × height (cm)^0.725 × weight (kg)^0.425. It was historically the first BSA formula and is still used in some protocols. It tends to give slightly lower values than Mosteller in small children.

When is BSA dosing used instead of mg/kg?

BSA-based dosing is preferred for drugs with a narrow therapeutic index and high inter-patient variability — most commonly chemotherapy agents, some immunosuppressants, and certain antifungals. For everyday antibiotics and analgesics, mg/kg is standard.

Is there a minimum or maximum BSA cap?

Many chemotherapy protocols cap BSA at 2.0 m² to avoid overdosing in overweight or tall patients. This tool shows you the calculated BSA without a cap — the prescribing physician or pharmacist applies protocol-specific caps when writing the order.

How accurate are these formulas in neonates and infants?

Both Mosteller and DuBois were derived from adult and older child data. Accuracy in neonates (under 1 month) and very small infants is lower. Specialized formulas (e.g., Haycock) are sometimes preferred for that population. Always follow your institution's protocol.

Can I use this tool for adults?

Yes. The formulas are valid for adults too. Enter the adult's height and weight and proceed the same way. The tool does not restrict to pediatric weights only.

Pediatric BSA Dose Calculator

Enter a child's height and weight to calculate BSA with Mosteller or DuBois formulas, then compute a drug dose in mg from a prescribed dose per m².

Patient Measurements

Height

Weight

Prescribed Dose (mg/m²) — optional

Leave blank to calculate BSA only.

Body Surface Area (BSA)

Mosteller

—

m²

DuBois

—

m²

Mosteller: √[(H cm × W kg) / 3600]. DuBois: 0.007184 × H^0.725 × W^0.425.

Formula Reference

Mosteller: BSA = √[(height cm × weight kg) ÷ 3600]

DuBois: BSA = 0.007184 × H^0.725 × W^0.425

Results are estimates. Protocol-specific BSA caps (e.g., 2.0 m²) are applied by the prescriber, not this tool.

Summary

This tool calculates body surface area (BSA) for pediatric patients using the Mosteller and DuBois formulas — the two most widely used methods in clinical practice. Enter the child's height and weight to get BSA in m², then enter a prescribed dose per m² to obtain the total dose in mg. BSA-based dosing is commonly used for chemotherapy, immunosuppressants, and other drugs where weight-based dosing alone may lead to under- or over-dosing in children. Always verify with a licensed prescriber before administering any medication.

How it works

Enter the child's height (cm or inches) and weight (kg or lb).
Select the BSA formula: Mosteller (most common in pediatrics) or DuBois.
The calculator computes BSA in m² using the chosen formula.
Enter the prescribed dose in mg per m² (mg/m²).
The tool multiplies BSA by the mg/m² dose to give the total dose in mg.
Review both formula results side by side to compare estimates.

Use cases

Calculate a chemotherapy dose for a pediatric oncology patient.
Determine the correct methotrexate dose for a child based on BSA.
Verify a prescribed BSA-based drug dose against your own calculation.
Compare Mosteller vs DuBois BSA estimates for the same patient.
Support pharmacokinetics coursework and clinical education.
Estimate BSA-based dosing for immunosuppressant therapy in children.
Double-check a dose before dispensing in a pediatric pharmacy.
Teach the difference between mg/kg and mg/m² dosing paradigms.

Frequently Asked Questions

Last updated: 2026-06-18 · Reviewed by Nham Vu