IV Drip Calculator
IV mL per hour and drops per minute.
What it does
IV orders state bags over hours while gravity sets drip by drops: milliliters per hour divided into minutes times the set factor. This page runs both lines with rounding to whole drops.
The default is a liter over 8 hours on a 15 set. Hourly is 125 mL/hr and drops round to 31 per minute. A 500 mL bag over 4 hours matches the same hourly pace the same way.
Factor follows the set on the package: 10, 15, or 20 for standard blood and fluid sets with 60 for microdrip burettes. Pumps skip drops and run the hourly line straight.
Bedside rules beat math. Independent double checks, pump libraries, and allergy bands all gate infusions that arithmetic alone cannot clear.
How to use
- Enter bag volume in mL.
- Enter hours ordered.
- Enter the set drip factor.
- Read mL/hr first.
- Read gtt/min next for gravity sets.
Formula
- volume
- Bag volume in milliliters.
- hours
- Infusion hours ordered.
- factor
- Set drops per milliliter.
Health aid for study and double checks only, never an order; pumps and pharmacy rule bedside care. Drip factors are 10, 15, 20, or 60 (microdrip) per set. Drops round to whole numbers while pumps use mL per hour.
Worked example
Example: liter over 8 hours
1,000 mL over 8 hr with 15 gtt/mL set.
- Hourly: 1,000 / 8 = 125 mL/hr.
- Per minute: 125 / 60 = 2.083 mL/min.
- Drops: 2.083 x 15 = 31.25, round to 31.
- Check: 31 x 60 / 15 = 124 mL/hr near ordered.
- Tool shows 125 mL/hr and 31 gtt/min.
Reference table
| Factor | Math | Rate |
|---|---|---|
| 10 | 125 x 10/60 | 21 gtt/min |
| 15 | 125 x 15/60 | 31 gtt/min |
| 20 | 125 x 20/60 | 42 gtt/min |
| 60 | 125 x 60/60 | 125 gtt/min |
Limits
- Study aid only. Pharmacy orders rule.
- Gravity drops rounded; pumps differ.
- Four factors only.
- No drug dosing or compatibility.
Common mistakes
- Mixing minutes with hours.
- Using the wrong set factor.
- Reading drops as mL/hr on pumps.
- Skipping second checks.
- Rounding hourly instead of drops.
Try it yourself
Quick checks. Answers sit tucked under each question.
500 mL over 4 hr at 15?
125 mL/hr, 31 gtt/min.
1,000 mL over 10 hr at 20?
100 mL/hr, 33 gtt/min (100 x 20/60 = 33.3).
Questions
Hourly rate?
Volume over hours. Here 125 mL/hr.
Drops per minute?
Hourly times factor over 60. Here 31 gtt/min.
Drip factors?
10, 15, 20, or 60 microdrip. This page takes those four.
1,000 mL over 10 hr at 20?
100 mL/hr with 33 gtt/min at factor 20.
Pump alternative?
No. Pump programming and second checks rule bedside care.
Medical order?
No. This is math aid only, not an order.