Local arithmetic worksheet · not a prescription

Medication dose arithmetic checker

Convert an instruction you already received into a mass, liquid volume, or tablet/capsule count. This tool never chooses a medicine, dose, frequency, duration, or treatment.

  • Instructions required
  • Unit mismatch blocking
  • Runs in this browser

Possible overdose, poisoning, wrong medicine, or severe reaction?

Do not use this calculator to decide whether to wait. Contact your local emergency service, poison centre, pharmacist, or urgent medical service now. Trouble breathing, collapse, seizure, facial or throat swelling, confusion, or extreme drowsiness needs emergency help.

Before entering anything

Copy the written instruction exactly

Use the prescription, medicine label, discharge instruction, or a pharmacist's written direction. If the instruction, unit, route, frequency, medicine name, or label concentration is unclear, stop and ask the clinician or pharmacist.

1. Confirm the instruction source

The name does not affect the arithmetic and is never checked against a drug database.

2. Enter the instructed dose

This amount is treated as user-supplied. The tool cannot tell whether it is clinically appropriate or whether it applies per dose, per day, or by a particular route.

3. Choose what to check

Sources and freshness

Medication-safety context, not a dosing database

Checked 26 July 2026. These sources support the page's safety boundaries; they do not validate any entered medicine or dose.

WHO: Medication Without HarmMedication errors can occur across prescribing, preparation, dispensing, administration, and monitoring. WHO: Patient safetyMedication errors are among common avoidable adverse events. US FDA: oral-liquid dosing designationsLiquid volume measurement requires clear label units and a dosing device.

How the arithmetic works

For a fixed instruction, the entered mass is the working amount. For a weight-based instruction, the entered amount per kilogram is multiplied by the entered weight after pounds are converted to kilograms. For a liquid label, the mass is divided by the label's mass-per-millilitre concentration. For a tablet or capsule, the mass is divided by the strength of one whole unit.

Mass units are normalized only between micrograms, milligrams, and grams. The checker deliberately rejects unsupported units, percentages, mixed concentration formats, zero values, non-finite values, and implausibly large arithmetic outputs that are more likely to be entry errors. These guards are not clinical maximum doses.

Does a successful result mean the dose is safe?

No. It means only that the entered numbers and supported units can be combined mathematically. A clinician or pharmacist must confirm the medicine, dose, route, timing, patient factors, and formulation.

What if the result is part of a tablet?

The page reports the exact mathematical count and warns that the formulation cannot deliver it as whole units. Do not split, crush, open, or substitute a medicine unless a pharmacist or clinician confirms that action for the exact product.

Can I use teaspoons for a liquid?

No. This checker uses millilitres only. Copy the mL concentration from the label and use the supplied oral syringe, cup, or other calibrated device as instructed by a pharmacist or clinician.