IV Drip Rate Calculator
Calculates the gravity drip rate in drops per minute and the flow rate in mL/hr — the standard nursing dosage-calculation formulas.
Formulas
- gtt/min = volume (mL) × drop factor (gtt/mL) ÷ time (min)
- mL/hr = volume (mL) ÷ time (hr)
- gtt/min = mL/hr × drop factor ÷ 60
Worked example: 1,000 mL over 8 hours with a 15 gtt/mL set → 1,000 × 15 ÷ 480 min = 31.25 ≈ 31 gtt/min; flow rate 125 mL/hr.
Quick-reference chart (gtt/min)
| Volume / time | 10 gtt/mL | 15 gtt/mL | 20 gtt/mL | 60 gtt/mL |
|---|---|---|---|---|
| 100 mL / 30 min | 33 | 50 | 67 | 200 |
| 100 mL / 1 hr | 17 | 25 | 33 | 100 |
| 250 mL / 1 hr | 42 | 63 | 83 | 250 |
| 500 mL / 4 hr | 21 | 31 | 42 | 125 |
| 1000 mL / 8 hr | 21 | 31 | 42 | 125 |
| 1000 mL / 10 hr | 17 | 25 | 33 | 100 |
Using an infusion pump instead? Pumps are set in mL/hr — see the mL per hour calculator.
FAQ
What is the IV drip rate formula?
Drops per minute (gtt/min) = total volume (mL) × drop factor (gtt/mL) ÷ time (minutes).
What is a drop factor?
The number of drops that make 1 mL for a particular IV administration set. It is printed on the tubing package: macrodrip sets are commonly 10, 15 or 20 gtt/mL; microdrip sets are 60 gtt/mL.
How do I convert mL/hr to drops per minute?
gtt/min = mL/hr × drop factor ÷ 60. With a 60 gtt/mL microdrip set, gtt/min equals mL/hr.
Should I round drops per minute?
Gravity drips are counted in whole drops, so the result is usually rounded to the nearest whole number. Follow your institution's policy.
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