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Weight-Based Dosage Calculator

Enter the weight and the ordered mg/kg dose to get the per-dose and daily amount.

1. Inputs

Enter the numbers and the result appears on the right.

kg
mg/kg
doses / day

2. Result

The per-dose amount to administer.

—
mg / dose
—
Daily amount (mg)
—
Doses per day
—
Pediatric fluid (mL/day)
—
Weight (kg)

To convert to mL, you need the solution concentration (mg/mL). Divide the per-dose amount (mg) by the concentration (mg/mL).

Formula & steps

How the calculation works

Per-dose amount = weight (kg) × ordered dose (mg/kg/dose)
Daily amount = per-dose amount × doses per day
If daily dose is ordered: per-dose = daily amount ÷ doses
mL amount = per-dose (mg) ÷ concentration (mg/mL)
1

Enter weight

Add the measured weight in kg.

2

Enter the ordered dose

Choose whether it is per dose or per day.

3

Check the per-dose amount

Convert to mL using the concentration if needed.

Questions

Frequently asked questions

Per-dose amount = weight (kg) × ordered dose (mg/kg). If the daily dose is ordered, divide the daily dose by the number of doses per day to get the per-dose amount.
The Holliday-Segar method is commonly used: 100 mL/kg/day for the first 10 kg, 1000 mL plus 50 mL/kg for each kg between 10 and 20 kg, and 1500 mL plus 20 mL/kg for each kg over 20 kg.
You need the solution concentration (mg per mL). Divide the per-dose amount (mg) by the concentration (mg/mL) to get the mL to administer. Check the drug label or order for the concentration.
Weighing the patient is the standard. Weight-based dosing is inaccurate without a measured weight. Follow your facility's policies.
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Disclaimer: This tool is a calculator intended for learning and verification support and is not a medical device. Always follow the order, your facility's policies and the clinical judgment of a licensed professional. We are not liable for any errors in the calculated results.