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Weight-Based Dosage Calculator

Weight-based dosing arithmetic, with the single and daily caps applied and the liquid volume worked out from the concentration on the bottle. It computes what you tell it to compute and does not know the drug.

Also called: mg per kg calculator, paediatric dose calculator.

kg
mg
mg
mg
mg

Milligrams per 5 mL, as printed on the bottle.

Dose
270

270 mg per dose, 4 times a day, giving 1,080 mg in twenty four hours. Neither cap binds at this weight, so the weight-based dose applies as calculated. At 120 mg per 5 mL that is 11.3 mL per dose. Check that the concentration is per 5 mL and not per mL; reading it wrong is a fivefold error.

Daily total
1,080
Volume per dose
11.25
Volume per day
45
Dose before any cap
270
Share of the daily maximum
27%
On the caps
Neither cap binds at this weight, so the weight-based dose applies as calculated.
On measuring it
At 120 mg per 5 mL that is 11.3 mL per dose. Check that the concentration is per 5 mL and not per mL; reading it wrong is a fivefold error.
What to check
This page does not know the drug, the indication, or the patient. Check the result against the prescription and the product label before anything is given.
How this is calculated

For reference only. Verify against your clinical protocol before acting on this number.

Through the day

DoseMilligramsMillilitresCumulative mg
Dose 127011.3270
Dose 227011.3540
Dose 327011.3810
Dose 427011.31,080
Method and background

This is what the calculation gives for the numbers you entered. It is an estimate, not advice, and it knows nothing about your situation beyond those numbers. Rules for India change on a published schedule; the effective date is shown on every rule-based tool.

How this is calculated

The weight-based dose is multiplied out, then capped: above a certain weight the per-kilogram figure passes the adult maximum, and the cap is what applies from there. The daily total is checked separately, since a schedule can breach the daily limit while every individual dose is legal. The volume conversion is where errors actually happen in practice, because a concentration printed as milligrams per five millilitres is easy to read as milligrams per millilitre, which is a fivefold overdose. The page shows both the milligrams and the millilitres so the two can be checked against each other.

weight times the per-kilogram dose, then capped, because the weight-based figure exceeds the adult maximum in larger patients
w
Weight in kilograms
d
Dose per kilogram

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

a child at 15 mg per kg

Patient weight
18 kg
Dose per kilogram
15 mg
Doses per day
4
Maximum single dose
1,000 mg
Maximum daily dose
4,000 mg
Concentration of the liquid
120 mg

Dose270

18 x 15, four times daily, at 120 mg per 5 mL

Open this example

the single-dose cap binds in an adult

Patient weight
90 kg
Dose per kilogram
15 mg
Doses per day
4
Maximum single dose
1,000 mg
Maximum daily dose
4,000 mg
Concentration of the liquid
120 mg

Dose1,000

boundary: 1350 mg would breach the single-dose maximum

Open this example

Method and limits

What it assumes

  • Actual body weight, which is not the right basis for every drug.

What it deliberately does not model

  • This calculator does not know the drug, the indication, renal or hepatic function, or any interaction. It multiplies the numbers you give it.
  • Some drugs dose on ideal or adjusted body weight, or on body surface area, and this page does none of those.
  • Always check the result against the prescription and the product label before administering anything.

Formula version 1.0.0 · definition 1.0.0 · India · Report a problem with this calculator

Frequently asked questions

Why is my dose lower than weight times the per-kilogram figure?
Because a cap applied. Above a certain weight the weight-based dose exceeds the maximum single dose, and the maximum is what governs from that point.
Why does the volume matter so much?
Because concentration is usually printed per 5 mL and misread as per mL. That single misreading is a fivefold overdose, which is why both figures are shown here.