Nursing

Tablet & Capsule Dose Calculator

The tablet and capsule dose calculator works out exactly how many solid oral tablets or capsules to give a patient when the ordered dose and available tablet strength differ. This is the most common type of nursing drug calculation — for example, when 500mg paracetamol is ordered but only 250mg tablets are available. The formula is simply Desired ÷ Have, applied to the tablet strength rather than a liquid concentration.

Tablets / Capsules to Give

Formula

Tablets = (Desired Dose ÷ Have) × Quantity

Example: Ordered 500mg, have 250mg tablets
= (500 ÷ 250) × 1 = 2 tablets
📖 Formula source: Standard nursing pharmacology formula. Potter & Perry's Fundamentals of Nursing, Elsevier.

Nursing Safety Tips

If the result is more than 3 tablets for a single dose, double-check the order with the prescriber — it may indicate a transcription error or an unusual dose.

Capsules must never be split or crushed unless specifically formulated as sprinkle capsules. Scored tablets may only be halved if they have a visible score line.

Related Calculators

Frequently Asked Questions

How many tablets should I give if the result is more than 3?

If the calculated result exceeds 3 tablets for a single dose, this is a red flag. Verify the order with the prescriber before administering — it may indicate a prescribing error, an unusual dose, or a mismatch between available and required strength.

Can I split any tablet in half?

Only tablets with a visible score line are safe to split. Enteric-coated, modified-release, and film-coated tablets must never be split or crushed, as this destroys the release mechanism and can cause toxicity or ineffectiveness.

Always verify calculations with a second nurse for high-alert medications. Follow your institution's 5 Rights of medication administration.