How to Convert Hours and Minutes for Infusion Calculations
Time conversion is one of the most common reasons a correct formula produces a wrong result. The conversion direction depends on the unit required by the formula.
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Formula
minutes ÷ 60 = decimal hours; hours × 60 = minutes
Minutes to decimal hours
Divide minutes by 60. Fifteen minutes is 0.25 hours, thirty minutes is 0.5 hours and forty-five minutes is 0.75 hours.
Do not write 45 minutes as 0.45 hours. Decimal notation is based on tenths and hundredths, while an hour contains sixty minutes.
Hours to minutes
Multiply hours by 60. Two hours is 120 minutes, four hours is 240 minutes and 7.5 hours is 450 minutes.
Decimal hours back to hours and minutes
Keep the whole-number part as hours. Multiply the decimal remainder by 60. For 1.6 hours, keep 1 hour and calculate 0.6 × 60 = 36 minutes, giving 1 hour 36 minutes.
Quick conversion table
- 0.25 hours = 15 minutes
- 0.5 hours = 30 minutes
- 0.75 hours = 45 minutes
- 1.25 hours = 1 hour 15 minutes
- 1.5 hours = 1 hour 30 minutes
- 1.75 hours = 1 hour 45 minutes
Check the formula unit
An mL/hour calculation needs hours. A gtt/min calculation needs minutes. Write the target unit beside the formula before converting.
Continue practising
Related learning
Content status and sources
This page is an original DosePractice public-beta learning resource. It remains subject to continuing educational, regulatory and editorial review; corrections are published when issues are identified.
- Nursing and Midwifery Council programme standards require health numeracy assessment related to medicine calculation, but DosePractice is not an NMC assessment or approved programme.
- Formula presentation should be independently reviewed against current tutor-approved or institutional teaching material before search indexing is enabled.
Review references
- NMC standards for pre-registration nursing programmes
- University of Southampton drug-calculation learning guide
- York St John University nursing formula sheet
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