Weight-Based Dosage (mg/kg)

Excel Formulas › Healthcare & Medical

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Many medications are dosed per kilogram of body weight. Multiply the dose per kg by the patient’s weight for the total dose — the foundational weight-based dosing calculation.


Quick formula: total dose from mg/kg and weight:
=dose_per_kg * weight_kg
Dose per kilogram times weight in kilograms gives the total dose; divide by concentration for volume.

The example

5 mg/kg, 70 kg patient.

AB
1ItemValue
2Dose 5 mg/kg—
3Weight 70 kg→ 350 mg

The formula

The formula:

=B2 * B3 // mg/kg × kg

How it works

How it works:

  1. Multiply the dose per kg by the patient’s weight in kg for the total dose.
  2. Convert pounds to kg first if needed: weight_lb / 2.205.
  3. To find the volume to give: total_dose / concentration (mg ÷ mg/mL).
  4. Divide a daily dose by the number of doses per day for each administration.

Educational use only. These are general Excel formulas for learning spreadsheet techniques — not medical advice or a substitute for clinical judgment, professional guidelines, or verified dosing references. Always confirm calculations against authoritative sources and institutional protocols.

Try it: interactive demo

Live demo

Dose per kg, weight, concentration.

Dose · Volume

Variations

Pounds to kg first

Convert weight:

=dose_per_kg * (weight_lb / 2.205)

Volume to administer

Dose ÷ concentration:

=total_dose / concentration

Per-dose amount

Split a daily dose:

=daily_dose / doses_per_day

Pitfalls & errors

Weight in kg. Convert pounds (÷2.205) before multiplying by mg/kg.

Check a max dose. Many drugs cap regardless of weight — clamp with MIN where appropriate.

Units throughout. mg, mg/kg, mg/mL must stay consistent.

Practice workbook

📊
Download the free Weight-Based Dosage (mg/kg) practice workbook
A dosage sheet with the lb-to-kg, volume, and per-dose variants, plus 4 challenges with answers. No sign-up required.

Frequently asked questions

How do I calculate a weight-based dose in Excel?
Multiply dose per kg by weight in kg: =dose_per_kg * weight_kg. 5 mg/kg for a 70 kg patient is 350 mg.
How do I convert pounds to kilograms for dosing?
Divide pounds by 2.205: =weight_lb / 2.205.
How do I find the volume to administer?
Divide the dose by the concentration: =total_dose / concentration (mg ÷ mg/mL).

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