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Dosage Calcs

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IV Flow Rate Calculator

Find the rate in milliliters per hour (mL/hr) for an infusion pump from the ordered volume and time.

IV Flow Rate Calculator

Volume (mL) ÷ Time (hr) = mL/hr

The ordered volume.

Unit: mL

The ordered time. Minutes are converted to hours.

Calculated in your browser. Values are not saved or sent anywhere.

Flow rate

Enter the volume and the time it should run over, then select Calculate.

Example: 100 mL ÷ 0.5 hr = 200 mL/hr

Educational Use & Safety

Educational and calculation use only. Dosage Calcs performs mathematical calculations using the values you enter. It does not determine whether a medication, dose, route, frequency, concentration, or infusion rate is appropriate or safe for a patient. Always verify medication orders, calculations, product labeling, and applicable clinical or institutional policies before medication administration. When in doubt, consult an appropriate licensed healthcare professional or pharmacist.

Educational Use & Safety

Educational use: You supply the ordered volume and time. This tool does not decide how fast any fluid or medication should run. Learn more.

What this calculates

Electronic infusion pumps are usually programmed in mL/hr. When an order gives a volume and a length of time, the rate is how many milliliters must run each hour to finish on time.

Formula and inputs

Volume (mL) ÷ Time (hr) = Rate (mL/hr)

  • Volume — the amount to infuse, in mL.
  • Time — how long the infusion should take, in hours or minutes.

If you need gravity tubing instead of a pump, use the IV drip rate calculator, which gives drops per minute.

Converting minutes to hours

Because the answer is per hour, time in minutes is divided by 60 first. The calculator shows this step.

30 min ÷ 60 = 0.5 hr

Worked examples

Example 1: time in hours

200 mL ÷ 2 hr = 100 mL/hr

Example 2: a longer infusion

1,000 mL ÷ 8 hr = 125 mL/hr

Example 3: time in minutes

30 min ÷ 60 = 0.5 hr

100 mL ÷ 0.5 hr = 200 mL/hr

Example 4: a short infusion

15 min ÷ 60 = 0.25 hr

50 mL ÷ 0.25 hr = 200 mL/hr

Common mistakes

  • Dividing by minutes and calling the answer mL/hr. 100 mL over 30 min is 200 mL/hr, not 3.3 mL/hr.
  • Dividing time by volume instead of volume by time.
  • Mixing up mL/hr (pump) with gtt/min (gravity tubing).
  • Forgetting to convert liters to milliliters (1 L = 1,000 mL) before dividing.

Rounding

Results that end are shown exactly. Repeating results are shown with ≈ and labeled approximate. Pumps differ in whether they accept whole numbers or tenths, so the rate you enter depends on the device and your course or facility policy.

What this tool does not do

It has no list of fluids or drugs and no recommended rates. It only divides the volume by the time you enter.

FAQ

Is mL/hr the same as the drip rate?

No. mL/hr is for pumps. Gravity tubing is counted in drops per minute (gtt/min) and needs the tubing's drop factor.

Can I enter liters?

Enter milliliters. Convert liters first: 1 L = 1,000 mL. The unit converter can help.

How long will a bag last at a given rate?

Use the infusion time calculator.

Sources

Formulas, units, and terminology were checked against these open references. Wording on this page is our own.

All sources · How we build and test calculators