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IV Drip Rate Calculator

Calculate the IV drip rate in drops per minute from the volume, infusion time and drop factor. Press Calculate.

Written and reviewed by SM Arijul Islam · Last reviewed 27 October 2026 · Editorial standards · Report an error

About the IV Drip Rate Calculator

An IV drip rate is set by counting drops, so the prescription in mL/hour has to be translated through the giving set's drop factor. A macrodrip set is typically 10, 15 or 20 drops per mL; a microdrip set is 60 drops per mL, where 1 drop is 1 mL/60.

The formula is volume in mL × drop factor ÷ time in minutes. A 500 mL bag over 4 hours with a 20 gtt/mL set is 500 × 20 ÷ 240 = 41.7 gtt/min. Always check the giving set packaging, because the drop factor is a property of the set, not the fluid.

How the calculation works

Drops per minute = (volume mL × drop factor) ÷ time in minutes.
mL per hour = volume mL ÷ time in hours.
Total drops = volume mL × drop factor.
Microdrip = 60 gtt/mL; macrodrip is usually 10, 15 or 20 gtt/mL.

Reference values

Drip rates for common giving sets
Drop factor	500 mL / 4 h	1,000 mL / 8 h	100 mL / 30 min
10 gtt/mL	21 gtt/min	21 gtt/min	33 gtt/min
15 gtt/mL	31 gtt/min	31 gtt/min	50 gtt/min
20 gtt/mL	42 gtt/min	42 gtt/min	67 gtt/min
60 gtt/mL	125 gtt/min	125 gtt/min	200 gtt/min

Worked example: three giving sets

A 1,000 mL bag over 8 hours with a 15 gtt/mL set runs at 1,000 × 15 ÷ 480 = 31.25, rounded to 31 gtt/min. The same bag with a 20 gtt/mL set runs at 41.7 gtt/min. For a 100 mL antibiotic over 30 minutes with a 60 gtt/mL microdrip, the rate is 200 gtt/min—too fast to count manually, so use a pump.

Round to the nearest whole drop and check the total volume over time. A small rounding error is acceptable for gravity infusion, but a pump is safer for precise, small-volume or high-risk infusions. Always confirm the drop factor on the giving set packaging; it is a property of the set, not the fluid.

Frequently asked questions

Is this for gravity or pump infusion?

The drop-count formula is for gravity sets. An infusion pump is programmed in mL/hour and does not need a drop factor.

Why does the drop factor matter so much?

A 20 gtt/mL set delivers three times the drops of a 60 gtt/mL microdrip set for the same volume. Using the wrong factor changes the dose by the same ratio.

Should I round the rate?

Round to the nearest whole drop for counting, then verify the volume delivered over 15–30 minutes. For critical infusions, use a pump.

What if the drop rate is not a whole number?

Round to the nearest whole drop and check the total volume over time. For precise or small-volume infusions, use a pump rather than counting drops.

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Medical disclaimer

This tool is for general information and education only. It is not medical advice, a diagnosis or a treatment plan, and it is not a substitute for a qualified healthcare professional. Clinical values, doses and drip rates vary with the patient, the equipment and local protocol, so confirm them against the current standard or prescription and consult the clinician responsible for care.