Dose Adjustment Calculator By Body Surface Area

Adjusts medicine dosage based on standard dose, weight and height of the patient.

You can read more about how the new dosage is calculated and about dose adjustment factors in the text below the form.

The dose adjustment calculator allows medical professionals to tailor the drug dosage to individual patient characteristics (height and weight).

This is often a recommendation in the case of many drugs to avoid over or under medication.

There are two formulas that are used in the calculation:

BSA (DuBois formula) = 0.007184 x (Height in cm)0.725 x (Weight in kg)0.425

Adjusted dose = Standard dose x BSA / 1.73

Both standard and adjusted dose can be in milligrams, micrograms or grams as measurement unit.

Standard dose:*
Measurement unit for adjusted dose:*
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Steps on how to print your input & results:

1. Fill in the calculator/tool with your values and/or your answer choices and press Calculate.

2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.

Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.


Dose adjustment algorithm

There are four fields in the dose adjustment calculator:

■ In the Standard dose field the user should input the recommended drug dosage as prescribed and choose between milligrams, micrograms or grams as measurement unit.

■ In the Height field, the patient height should be input in either centimeters or inches.

■ In the Weight field, patient weights are accepted in kilograms or in lbs.

■ The user can also set the Measurement unit for adjusted dose, a feature especially useful when the preferred unit is different from the standard dose unit.

The algorithm used by the calculator has two steps.

■ First step: transforms any measurements input by the user from the Imperial system to the Metric system if needed and employs the patient height and weight in the following body surface area formula:

DuBois BSA formula = 0.007184 x (Height in cm)0.725 x (Weight in kg)0.425

■ The second step: associates the BSA value with the input standard dose:

Adjusted dose = Standard dose x BSA / 1.73


Dose adjustment factors

Recommended drug dosage regimens are often tailored to the needs of individual patients in many conditions and clinical settings.

Beside the patient variables taken into account in the dose adjustment calculator (patient height and weight), there are other elements to factor in.

These include patient age, gender, comorbidities acute, or chronic character or the severity of the disease.

Pharmacological effects, medicine half time, route of administration, metabolism and elimination are also to be taken in consideration when deciding the administration frequency.

When the patient is under several medications, synergism and antagonism effects of drugs are also accounted for.



1. Du Bois D, Du Bois EF. A formula to estimate the approximate surface area if height and weight be known. Archives of Internal Medicine. 1916; 17 (6): 863–71.

2. Pai MP. Drug dosing based on weight and body surface area: mathematical assumptions and limitations in obese adults. Pharmacotherapy. 2012; 32(9):856-68.

Specialty: Pharmacology

Objective: Determination

Type: Calculator

No. Of Variables: 4

Article By: Denise Nedea

Published On: March 22, 2017 · 07:55 AM

Last Checked: March 22, 2017

Next Review: March 22, 2023