Solid dosage forms and oral liquids
Tablet and oral liquid calculations
How to calculate the number of tablets and the mL of an oral liquid, and what to consider with splitting and modified-release products.
Tablets
Work out the number of tablets from the dose and the strength.
Oral liquids and drops
The strength is often given in mg/mL.
The number of drops per mL varies between products, so use the figure given in the question or in the product information. Amounts are measured with an oral syringe or dosing cup, not with household spoons.
Read the strength
Is it given in mg/mL, mg/5 mL or as a percentage?
Convert to the same unit
The dose and the strength must be in the same unit before you divide.
Check the answer
Is the amount sensible to give? A very large or very small amount is a warning sign.
More on calculations can be found in the dosage calculator and the DSM triangle.
Frequently asked questions
How do you calculate the number of tablets?+
Divide the prescribed dose by the strength per tablet.
Can all tablets be split?+
No. Only split tablets that are designed for it. Modified-release and enteric-coated tablets should normally not be split or crushed. Check the product information.
How do you calculate the mL of an oral liquid?+
Divide the dose by the strength in mg/mL.
How many drops are in a mL?+
It varies between products. Use the figure in the product information or the question.
Practise tablets and liquids
Practise calculating the number of tablets and mL in practice questions, with the calculator next to each question. Dos is a practice app for drug calculations, with practice tests of ten questions, a built-in calculator next to each question and statistics per topic.
