How to use this calculator
- Enter or choose volume to infuse.
- Enter or choose infusion time: hours.
- Enter or choose infusion time: minutes.
- Enter or choose start time.
- The flow rate updates as you type. Use Copy result or Share to keep it.
Method
Flow rate (mL/h) = Volume (mL) ÷ Time (h); Finish time = Start time + Infusion time
- Volume
- fluid to infuse, in mL
- Time
- prescribed infusion time
Worked example
- Flow rate = 500 mL ÷ 4 h = 125 mL/h.
- Per minute = 500 ÷ 240 = 2.083 mL/min.
- Finish = 08:00 + 4 h = 12:00.
500 mL over 4 hours runs at 125 mL/h and, started at 08:00, finishes at 12:00.
What the result means
Programme the pump with the mL/h rate and the volume to be infused, then confirm against the prescription. For gravity sets, convert to drops per minute with the drip rate calculator.
Assumptions and limits
- The rate is constant for the whole infusion.
- Line priming volume, interruptions and bag overfill are not included.
- Weight-based or dose-based rates (for example mg/kg/h) are not calculated here.
Questions
How do I convert mL/h to drops per minute?
Multiply mL/h by the drop factor and divide by 60. At 125 mL/h on a 10 gtt/mL set that is 20.8, about 21 gtt/min.
Why might the infusion finish later than shown?
Pauses for alarms, line changes or patient movement add time; the finish time assumes no interruptions.
Sources
Please note: This is a general screening estimate for adults, not medical advice or a diagnosis. Talk to a qualified health professional about your health.