Free resources · Dosage calculations
Liquid oral doses
How many millilitres of a liquid medication supply the ordered dose.
Worked example: learn the method
Ungraded teaching example with different numbers from the practice exercise. For study only, not clinical use.
An order reads 200 mg. The medication is supplied as 200 mg per 5 mL. How many millilitres supply the ordered dose?
(Desired dose ÷ dose on hand) × volume on hand = millilitres to give
- Set up the ratio: 200 mg ÷ 200 mg = 1
- Multiply by the supplied volume: 1 × 5 mL = 5 mL
- Units cancel: mg ÷ mg cancels, leaving mL — the unit you were asked for.
Example result: 5 mL. Round to the nearest tenth of a millilitre.
Common mistake to avoid: Keep the supplied volume in the ratio. A label expressed per several millilitres is not a strength per one millilitre.
Dosage formulas · Unit conversion reference
Problem
An order reads 800 mg. The medication is supplied as 200 mg per 5 mL. How many millilitres supply the ordered dose?
Round to the nearest tenth of a millilitre.
These are practice problems for exam preparation. Every number in them is generated by CARE for teaching purposes — nothing here is a real order and nothing here is a clinical dosing tool. Do not use this page to work out a dose for a real patient: use your facility's policy, the actual order, and an independent double-check where your policy requires one.
Medication calculations also appear inside real exam practice, mixed with everything else and scored the same way. Try a free quiz drawn from the actual question bank.
Free quiz →