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Drug Dose By Weight Calculator

Work out drug dose by weight instantly with clear inputs, formula shown and shareable results.

About Drug Dose By Weight Calculator

Multiplies body weight by the prescribed dose per kilogram, then converts the milligram dose into a volume using the preparation strength.

Formula

Weight-based dose

Dose (mg) = weight (kg) x dose per kg (mg/kg); volume (mL) = dose / concentration (mg/mL)

Worked example

With the default values below, Drug Dose By Weight Calculator returns Dose per administration of 350.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Body weightaccepts 0.5–250 kg
70 kg
Dose per kilogramaccepts 0.01–200 mg/kg
5 mg/kg
Concentration of the preparationaccepts 0.1–500 mg/mL
50 mg/mL
Doses per dayaccepts 1–6
3

Results

Dose per administration
350.00 mg
Volume to draw up
7.00 mL
Total daily dose
1,050.00 mg

Step by step

  1. 1Values used
  2. 2Weight-based dose
  3. 3Dose per administration= 350.00 mg
  4. 4Volume to draw up= 7.00 mL
  5. 5Total daily dose= 1,050.00 mg

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
  • This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

Should the dose be capped?

Many drugs have an adult maximum that overrides the weight calculation, especially in older children.

Which weight is used?

Depends on the drug: actual, ideal or adjusted body weight, as stated in the product literature.

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