What is a drop factor?

The drop factor is how many drops the IV giving set produces per millilitre, printed on the set packaging. Macrodrip sets deliver 10, 15, or 20 gtt/mL and microdrip sets deliver 60 gtt/mL. It is essential for converting volume to drops per minute.

How is drops per minute calculated?

Drops per minute equals the volume in mL multiplied by the drop factor in gtt/mL, divided by the total infusion time in minutes. For 1000 mL over 480 minutes with a 20 gtt/mL set, that is 1000 times 20 divided by 480, about 42 gtt/min.

When do I use mL/hr instead?

Use mL/hr when programming an electronic infusion pump, which controls flow directly by volume. Use drops per minute when running a gravity set and counting drops in the drip chamber. This tool gives both.

Should I round drops per minute?

Yes. You cannot count fractional drops, so round to the nearest whole drop per minute for a gravity set. The tool shows both the exact and the rounded value, plus the time between drops to help you set the roller clamp.

Is patient data stored?

No. Every calculation runs locally in your browser. Nothing you enter is transmitted or saved on a server.

IV Drip Rate Calculator

When an intravenous infusion is ordered as a volume over a time, staff must convert it into a flow rate the equipment can deliver: drops per minute for a gravity giving set, or mL/hr for a pump. This calculator does both from the same inputs.

How it works

Two formulas are applied:

mL/hr   = volume_mL / time_hours
gtt/min = (volume_mL * drop_factor_gtt_per_mL) / time_minutes

The drop factor is fixed by the giving set. Macrodrip sets deliver 10, 15, or 20 drops per millilitre and are used for routine fluids; microdrip sets deliver 60 drops per millilitre and are used for fine control such as pediatric or medication infusions.

Example

An order for 1000 mL of saline over 8 hours with a 20 gtt/mL macrodrip set: mL/hr is 1000 ÷ 8 = 125 mL/hr. Drops per minute is (1000 × 20) ÷ 480 ≈ 42 gtt/min, or about one drop every 1.4 seconds.

Notes

Always confirm the order, the giving set’s printed drop factor, and your facility’s policy. Round drops per minute to a whole number when running a gravity set. This tool is an educational aid and double-check, not a substitute for clinical judgment.