Step 1: Convert inputs to common units.
Step 2: Solve equation.
X = (D / H) × Q
X = (250 / 125) × 5
Result = Liquid Dose = 10 mL
The standard nursing formula for calculating the volume of a liquid medication to administer orally. D is the desired dose, H is the available (have) dose, and Q is the volume containing H.
X (volume) = (D / H) × Q
Enter the desired dose ordered by the prescriber, the available dose on the medication label, and the volume that contains the available dose. The calculator divides D by H, multiplies by Q, and returns the volume to administer in your chosen output unit (mL, L, tsp, or tbsp).
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?
Always use a calibrated oral syringe or medicine cup — household spoons are not precise enough for medication dosing.
P.O. (Latin: per os) means by mouth. This calculator covers oral liquid medications including solutions, syrups, and suspensions. The D and H values must be in the same mass unit before division. This calculator auto-converts between mg, g, and mcg.
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.