Free Tool
Liquid Dose Calculator (mL)
Calculate how many milliliters to administer from an ordered dose and concentration.
Formula
mL to give = (ordered dose × volume on label) ÷ dose on label
e.g. 250 mg per 5 mL → enter 250
e.g. 250 mg per 5 mL → enter 5
Result
Enter values above to calculate.
Worked example
Scenario: Order: Amoxicillin 500 mg PO. Available: Amoxicillin oral suspension 250 mg per 5 mL.
- 1Identify ordered dose (500 mg) and label values (250 mg per 5 mL).
- 2Apply formula: (500 × 5) ÷ 250 = 2500 ÷ 250 = 10.
Administer 10 mL.
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When to use this calculation
Use this calculation for any liquid medication — oral suspensions, IV push doses drawn from a vial, IM injections — when the order is in milligrams (or another mass unit) and you need to convert to a volume (mL) based on the concentration printed on the label. The formula is the same regardless of route.
Watch out for label-reading errors: '250 mg/5 mL' means 250 mg of drug per 5 mL of liquid (not per 1 mL). Always identify the dose AND the volume from the label before plugging numbers in. For pediatric doses, also double-check the calculated mL against age-appropriate single-dose limits before administering — a math-correct dose can still be unsafe.