# What is the IV drip rate?

Works out an IV drip rate in drops per minute from the volume, the infusion time, and the drop factor of the giving set, with the same infusion as a pump rate in mL per hour.

- Page: https://www.acalculator.org/health/drip-rate-calculator
- JSON spec: https://www.acalculator.org/health/drip-rate-calculator.json
- Version: 1cce0eecdff4

## Default answer

Example with the default inputs (Volume to infuse 1,000 mL, Infusion time 8 h, Drop factor (gtt/mL) 20): 1,000 mL over 8 h with a 20 gtt/mL set runs at 41.67 drops a minute (125 mL/h).

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| volume | Volume to infuse | The volume of fluid to give, from 1 mL to 10 L. |
| time | Infusion time | How long the infusion runs, from 1 minute to 72 hours. |
| df | Drop factor (gtt/mL) | Drops per mL of the giving set, printed on its package: often 10, 15, or 20 (macrodrip) or 60 (microdrip). |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| rate | Drip rate (gtt/min) | Volume in mL × drop factor ÷ time in minutes, to 2 decimals. |
| drops | Drops per minute, whole | The drip rate rounded to the nearest whole drop (halves up), which is what can be counted. |
| mlPerHour | Pump rate (mL/h) | Volume in mL ÷ time in hours, to 2 decimals. |

## Method

Drops per minute = volume (mL) × drop factor (gtt/mL) ÷ time (minutes). mL per hour = volume (mL) ÷ time (hours).

## Assumptions

- A gravity infusion at a steady rate; the drop factor is the one printed on the giving set.
- The page works out the rate for an order a clinician has written. It does not choose a fluid, a volume, or a time.
- The rate is worked from the exact typed values and rounded once: 2 decimals, and to a whole drop with halves up.

## Worked examples

1. volume = 0.001, time = 28,800, df = 20 gives rate = 41.666667, drops = 42, mlPerHour = 125. Source: Open RN Nursing Skills (Ernstmeyer et al.), 5.14: gtt/min = mL × gtt/mL ÷ min: 1000 × 20 ÷ 480 = 41.67.
2. volume = 0.0001, time = 1,800, df = 15 gives rate = 50, drops = 50, mlPerHour = 200.
3. volume = 0.00025, time = 7,200, df = 60 gives rate = 125, drops = 125, mlPerHour = 125.
4. volume = 0.0005, time = 14,400, df = 10 gives rate = 20.833333, drops = 21, mlPerHour = 125.
5. volume = 0.00005, time = 2,400, df = 15 gives rate = 18.75, drops = 19, mlPerHour = 75.

## FAQ

### How do you work out a drip rate?

Multiply the volume in mL by the drop factor of the giving set (drops per mL), then divide by the time in minutes. For 1,000 mL over 8 hours with a 20 drops/mL set: 1,000 × 20 ÷ 480 = 41.67, about 42 drops a minute.

### What is a drop factor?

The number of drops that make 1 mL with a given giving set. It is printed on the package. Macrodrip sets are usually 10, 15, or 20 drops per mL; microdrip sets are 60 drops per mL.

### Why do drops per minute equal mL per hour with a microdrip set?

A 60 drops/mL set gives 60 drops for each mL, and an hour has 60 minutes, so the two 60s cancel: drops per minute = mL per hour.

### Should I round the drip rate?

Drops can only be counted whole, so the page also shows the rate rounded to the nearest whole drop, halves up. The exact rate is shown to 2 decimals.

### What is mL per hour used for?

An infusion pump is set in mL per hour. The page divides the volume by the time in hours to give that rate for the same order.

### Does the page choose a fluid or a rate?

No. It only does the arithmetic for an order that a clinician has written: the volume, the time, and the set in use.

## Sources

- Ernstmeyer K, Christman E, eds. Nursing Skills (Open RN). 5.14 IV Infusion by Gravity (drop factors and drops per minute). https://med.libretexts.org/Bookshelves/Nursing/Nursing_Skills_(OpenRN)/05%3A_Math_Calculations/5.14%3A_IV_Infusion_by_Gravity (retrieved 2026-10-05)