IV Drip Rate Calculator (gtt/min and mL/h)
By Santaji GadepatilinUpdated October 27, 2026
IV infusions must run at the right rate. Nurses calculate drops per minute or mL per hour from the volume, time and drip set. This free IV drip rate calculator solves for whichever value you leave blank and shows the formula and steps.
How to use the IV drip rate calculator
Enter the volume to infuse, the time in hours and the drip factor of your IV set. You get the flow rate in mL/h (for infusion pumps) and the drip rate in drops per minute (for gravity sets).
This tool supports calculation practice. Always follow the prescription, local protocols and independent double-checks.
IV drip rate formulas
mL/h = volume ÷ hours · gtt/min = volume × drip factor ÷ minutes
Drip rate chart (drops per minute)
| Volume and time | mL/h | 10 gtt/mL | 15 gtt/mL | 20 gtt/mL | 60 gtt/mL |
|---|---|---|---|---|---|
| 100 mL over 0.5 h | 200 | 33 | 50 | 67 | 200 |
| 250 mL over 1 h | 250 | 42 | 62 | 83 | 250 |
| 500 mL over 4 h | 125 | 21 | 31 | 42 | 125 |
| 1000 mL over 6 h | 167 | 28 | 42 | 56 | 167 |
| 1000 mL over 8 h | 125 | 21 | 31 | 42 | 125 |
| 1000 mL over 12 h | 83 | 14 | 21 | 28 | 83 |
| 500 mL over 24 h | 21 | 3 | 5 | 7 | 21 |
Worked example
1,000 mL over 8 hours with a 20 gtt/mL set:
- Flow rate = 1,000 ÷ 8 = 125 mL/h
- Time in minutes = 480
- Drip rate = 1,000 × 20 ÷ 480 = 41.7 ≈ 42 drops/min
Counting drops
Count drops in the drip chamber for 15 seconds and multiply by 4, or count for a full minute for accuracy. Adjust the roller clamp until the count matches.
Infusion time from rate
Rearranged: time (h) = volume ÷ mL/h. 500 mL at 125 mL/h takes 4 hours. In the calculator, press × on Infusion time and enter the rate.
Macrodrip vs microdrip
- Macrodrip (10–20 gtt/mL): larger drops, for routine adult fluids.
- Microdrip (60 gtt/mL): small drops, for paediatrics and precise low rates.
Frequently asked questions
How do I calculate drops per minute?
Drops per minute = volume (mL) × drip factor (gtt/mL) ÷ time (minutes). 1,000 mL over 8 hours with a 20 gtt/mL set is about 42 drops per minute.
What is a drip factor?
The number of drops that make 1 mL with a particular IV set. It is printed on the packaging — commonly 10, 15 or 20 for macrodrip and 60 for microdrip sets.
Why is microdrip mL/h the same as drops per minute?
With a 60 gtt/mL set, drops per minute equals mL per hour, because there are 60 minutes in an hour.
Should I round drops per minute?
Yes, round to the nearest whole drop, as you cannot count part of a drop.