What is the IV flow rate formula?

Millilitres per hour equals the volume in mL divided by the time in hours.

Does the flow rate depend on the giving set?

Not for a pump. A pump is programmed in millilitres an hour and delivers that regardless of the tubing. The drop factor only matters for a gravity line, where the flow is counted in drops.

What if the infusion is written in minutes?

Convert to hours by dividing by 60, or switch the unit on the calculator. A 30-minute infusion of 100 mL runs at 200 mL/hr, because it would deliver 200 mL if it ran for a full hour.

IV Flow Rate Calculator

Pump rate

– mL/hr

Enter a volume and a time.

Per minute: –

The working

This works out the arithmetic. The order, the product in your hand and local policy still govern what is given.

The IV flow rate formula

mL/hr = volume in mL ÷ time in hours

A litre over eight hours is 1000 divided by 8, which is 125 mL/hr. An infusion written in minutes divides by 60 first, so 100 mL over 30 minutes is 200 mL/hr: the rate the pump would deliver if it kept going for a full hour, which is what a rate means.

Common IV rates

Volume	Over	Pump rate
1000 mL	8 hr	125 mL/hr
1000 mL	12 hr	83.3 mL/hr
1000 mL	24 hr	41.7 mL/hr
500 mL	4 hr	125 mL/hr
500 mL	8 hr	62.5 mL/hr
250 mL	1 hr	250 mL/hr
100 mL	30 min	200 mL/hr
50 mL	30 min	100 mL/hr

When a rate is not what the order gives you

This calculation assumes you already know the volume and the time. Two common orders do not give you those directly.

An order written per kilogram per minute gives a dose rate rather than a fluid rate, and the strength of the made-up bag has to convert one into the other. That is themcg/kg/min calculator.

A gravity line has no pump to programme, so the rate has to become a count of drops using the drop factor on the giving set, which is the drip rate calculator. Running the question backwards, from a rate to how long the bag lasts, is theinfusion time calculator.

Questions about IV flow rates

What is the IV flow rate formula?: Millilitres per hour equals the volume in mL divided by the time in hours.
How do I calculate mL/hr for 1000 mL over 8 hours?: 1000 divided by 8, which is 125 mL/hr.
Does the flow rate depend on the giving set?: Not for a pump. A pump is programmed in millilitres an hour and delivers that regardless of the tubing. The drop factor only matters for a gravity line, where the flow is counted in drops.
What if the infusion is written in minutes?: Convert to hours by dividing by 60, or switch the unit on the calculator. A 30-minute infusion of 100 mL runs at 200 mL/hr, because it would deliver 200 mL if it ran for a full hour.