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mL/hr From Dose Calculator

Turn an hourly drug dose into a pump rate in mL/hour from the amount of drug in the bag and the bag volume — the concentration does the conversion.

Ordered dose per hour

Drug in bag

Bag volume

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How it works

Concentration = drug(mg) ÷ bag(mL) · mL/h = dose per hour ÷ concentration

When a drip is ordered as an amount per hour (mg/h, units/h) rather than a volume, the pump rate is the dose divided by the bag concentration. Work out the concentration as drug amount over bag volume, then divide the hourly dose by it to get millilitres per hour. Keep the drug unit in the dose and the concentration identical — both in milligrams here — so the units cancel to leave mL/h.

Worked example

For a 2 mg/h order using a bag of 250 mg in 250 mL: concentration = 250 ÷ 250 = 1 mg/mL, so the rate = 2 ÷ 1 = 2 mL/h. If the same drug were 500 mg in 250 mL (2 mg/mL), the rate would be 2 ÷ 2 = 1 mL/h.

Sources: NIH/NLM DailyMed — drug labeling and dosing

Frequently asked questions

Does this work for units-per-hour drips?

Yes — enter the drug amount in the bag and the dose in the same unit (both in units, or both in milligrams). The concentration then comes out in units/mL and the rate in mL/h. For an insulin or heparin drip, use the matching dedicated calculator for the extra checks.

What if my order is per minute, not per hour?

Multiply a per-minute dose by 60 first to make it per hour, then divide by the concentration. This calculator expects an hourly dose; feeding it a per-minute figure without converting gives a rate 60 times too low.

Why does a stronger bag mean a slower rate?

A higher concentration packs more drug into each millilitre, so fewer millilitres deliver the same hourly dose. That is why double-strength bags are used for fluid-restricted patients — the same dose runs at half the volume.

Related calculators

mcg/kg/min Infusion Rate Calculator

Convert a weight-based mcg/kg/min order into a pump rate in mL/hour from the patient weight and the bag concentration, or work back from a running mL/h to the dose; also handles mcg/min, mcg/kg/h, mg/kg/h, mg/min, mg/h and ng/kg/min, with a titration table and bag time.

Units Per Hour Infusion Calculator

Read how many units per hour a pump is delivering from its mL/hour rate and the bag concentration — the reverse of setting a units-per-hour order.

IV Infusion Time Calculator

Find how long an IV will take to finish from the bag volume and the flow rate, with the completion time in hours and minutes.

Drops Per Minute Calculator

Convert a flow rate in mL/hour to drops per minute for a manual gravity IV set using the tubing’s drop factor — no volume or total time needed.

Educational estimate only — not medical advice, and no substitute for a clinician, pharmacist or the product label. Every dose, rate and volume must be independently verified against the actual drug, order and patient before administration. Do not use this tool to self-treat or to bypass an institution’s double-check policy.