Infusion Time Calculator
Infusion time
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Enter a volume and a rate.
- In decimal hours
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- Finishes at
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The working
The finish time assumes the infusion starts now and runs uninterrupted at this rate.
This works out the arithmetic. The order, the product in your hand and local policy still govern what is given.
The infusion time formula
time in hours = volume in mL ÷ rate in mL/hr
A litre at 125 mL/hr runs for eight hours. The decimal answer is converted into hours and minutes because 4.55 hours is not a useful thing to write on a chart, whereas 4 hr 33 min is.
Common volumes and rates
| Volume | Rate | Runs for |
|---|---|---|
| 1000 mL | 125 mL/hr | 8 hr |
| 1000 mL | 100 mL/hr | 10 hr |
| 1000 mL | 83 mL/hr | 12 hr 3 min |
| 500 mL | 125 mL/hr | 4 hr |
| 500 mL | 50 mL/hr | 10 hr |
| 250 mL | 250 mL/hr | 1 hr |
| 100 mL | 200 mL/hr | 30 min |
Running the same relationship the other way, from a time you want to a rate you need, is theIV flow rate calculator. On a gravity line the rate becomes a count of drops through the drip rate calculator.
Questions about infusion time
- How do I calculate infusion time?
- Divide the volume in mL by the rate in mL/hr. The answer is the time in hours.
- How long does 1000 mL at 125 mL/hr take?
- Eight hours. 1000 divided by 125 is 8.
- Does the calculated time account for line priming or interruptions?
- No. It is the running time for the volume at that rate. Priming volume, flushes, pauses and rate changes all shift the actual finish, so the figure is a planning estimate rather than a schedule.