Rex says
Same equations the textbooks use — just way less awkward. Pop in your stats and I'll tell you what the number actually means for you.
Try a scenario
Click to load — tweak from there.Inputs
Result
Dose per administration (mg)
270.0
Volume to draw (mL)
8.44
Total daily dose (mg)
1080
Remaining under daily max (mg)
920
Percent of daily max
54%
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter patient weight (kg).
- 2Enter ordered dose (mg/kg).
- 3Enter concentration (mg/mL).
- 4Enter doses per day.
- 5Enter max daily dose (mg).
- 6Read your dose per administration (mg) on the right — it updates as you type.
- 7Hit Share to keep the scenario or send it to someone.
About this calculator
Turn a mg-per-kilogram order into a total dose, then into the millilitres to draw given the concentration on the vial — with a daily total across scheduled doses.
Worked example
Using the values the calculator loads with:
Inputs
- Patient weight: 18 kg
- Ordered dose: 15 mg/kg
- Concentration: 32 mg/mL
- Doses per day: 4
- Max daily dose: 2000 mg
Results
- Dose per administration (mg): 270
- Volume to draw (mL): 8.44
- Total daily dose (mg): 1,080
- Remaining under daily max (mg): 920
- Percent of daily max: 54%
What each field means
Inputs
- Patient weight (kg)
- The patient weight used in the calculation, measured in kg. Starts at 18 kg so you have a working example on load.
- Ordered dose (mg/kg)
- The ordered dose used in the calculation, measured in mg/kg. Starts at 15 mg/kg so you have a working example on load.
- Concentration (mg/mL)
- The concentration used in the calculation, measured in mg/mL. Starts at 32 mg/mL so you have a working example on load.
- Doses per day
- The doses per day used in the calculation. Starts at 4 so you have a working example on load.
- Max daily dose (mg)
- The max daily dose used in the calculation, measured in mg. Starts at 2000 mg so you have a working example on load.
Results
- Dose per administration (mg)
- Returned as a decimal number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Volume to draw (mL)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Total daily dose (mg)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Remaining under daily max (mg)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Percent of daily max
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Pounds or kilograms?
Kilograms. Divide pounds by 2.205 first — mixing the two is the single most common dosing error.
What if the daily total exceeds the max?
Stop and re-check the order. This tool flags it but cannot decide for you.
Accuracy and limitations
- Population formulas describe averages; individual bodies vary, especially at the extremes of height, age, or muscle mass.
- Results do not account for medical conditions, medication, or pregnancy.
- Use this as a directional reference, not a diagnosis — talk to a clinician before acting on it.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Weight-Based Dosage Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/pediatric-dose
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/pediatric-dose" target="_blank" rel="noopener">Weight-Based Dosage Calculator — RevenueLab</a> (2026).</p>
Source: [Weight-Based Dosage Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/pediatric-dose) (2026).