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.
How it works
Concentration = units in bag ÷ bag(mL) · Units per hour = pump rate(mL/h) × concentration(units/mL)
Sometimes you need the reverse of a rate calculation: given the millilitres per hour a pump is set to, how many units per hour is the patient actually receiving? Divide the bag’s total units by its volume to get the concentration, then multiply by the mL/hour rate. This is a useful independent check when verifying a running heparin or insulin drip against the ordered units-per-hour. Confirm the bag’s true units and volume from its label.
Worked example
A pump running at 12 mL/h with 25,000 units in 250 mL: concentration = 25,000 ÷ 250 = 100 units/mL; delivered dose = 12 × 100 = 1,200 units/h.
Frequently asked questions
When would I calculate units per hour from the rate?
As a double-check. If a drip is running at a set mL/h, converting back to units/h confirms the delivered dose matches the order — a quick safety check at handover, on assuming care, or when a rate looks unexpected.
How is the concentration found?
Divide the total units in the bag by the volume in millilitres. A 25,000 units in 250 mL bag is 100 units/mL; a 25,000 units in 500 mL bag is 50 units/mL. The concentration must match the actual bag hanging, not a default.
Does this apply to insulin drips?
Yes — enter the insulin units in the bag and its volume. For the standard 100 units in 100 mL (1 unit/mL) mix, the units per hour equals the mL per hour. Use the insulin titration calculator when adjusting an insulin drip to a new order.
Related calculators
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.