Step 1: Convert inputs to common units.
Step 2: Solve equation.
X = (D / H) × Q
X = (250 / 125) × 5
Result = 10 mL
The liquid dosage formula X = (D / H) × Q is the standard method nurses use to calculate the volume of a liquid medication to administer. The label on the medicine bottle states the concentration — the mass of drug contained in a given volume of liquid (e.g., 250 mg per 5 mL).
P.O. (Latin: per os) means "by mouth" — this calculator covers oral liquid medications including solutions, syrups, and suspensions.
Calculate Liquid Dosage ↑A provider orders 500 mg of amoxicillin suspension. The pharmacy supplies a bottle labeled 250 mg per 5 mL. How many mL should the nurse administer?
X = (500 mg / 250 mg) × 5 mL = 10 mL
Always use a calibrated oral syringe or medicine cup for accurate measurement — household spoons are not precise enough for medication dosing.
Use the formula X = (D / H) × Q. Divide the desired dose by the available dose, then multiply by the quantity (volume). For example, if the order is 500 mg and the bottle reads 250 mg/5 mL, you get (500/250) × 5 = 10 mL.
Both use the same D/H × Q formula. For tablets, Q is the number of tablets per dose unit (usually 1) and the answer is in tablets. For liquids, Q is a volume (e.g., 5 mL) and the answer is in milliliters, teaspoons, or tablespoons.
Yes — use the Result Unit dropdown to display the answer in teaspoons (tsp) or tablespoons (tbsp). One teaspoon is approximately 5 mL. For clinical accuracy, always use a calibrated measuring device rather than household spoons.