Adding durations like 3 h 45 min + 2 h 30 min is easy to get wrong because minutes carry over at 60, not 100. Converting everything to minutes first avoids mistakes.
How to use the Hours and Minutes Calculator
- Duration 1 – hours
- Duration 1 – minutes
- Then
- Duration 2 – hours
- Duration 2 – minutes
- Then
- Duration 3 – hours
- Duration 3 – minutes
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter up to three durations and choose whether to add or subtract each.
Tips
- Check whether the end date should be included – event durations usually include it, elapsed time does not.
- Months have 28–31 days, so “one month” is counted by calendar date, not as 30 days.
- Use 24-hour time or set AM/PM carefully when entering clock times.
- Time zones and daylight-saving changes are not applied unless the calculator says so.
Common mistakes to avoid
- Counting a 30-day month when a calendar month is meant (or the reverse).
- Forgetting leap years when counting days across February.
- Mixing decimal hours (7.5 h) with clock time (7:30).
Inputs explained
| Field | What to enter |
|---|---|
| Duration 1 – hours | A number |
| Duration 1 – minutes | A number |
| Then | Choose one: Add, Subtract |
| Duration 2 – hours | A number |
| Duration 2 – minutes | A number |
| Then | Choose one: Add, Subtract |
| Duration 3 – hours | A number |
| Duration 3 – minutes | A number |
What each result means
- Total minutes = ([Duration 1 – hours]×60 + [Duration 1 – minutes]) + [Then]×([Duration 2 – hours]×60 + [Duration 2 – minutes]) + [Then]×([Duration 3 – hours]×60 + [Duration 3 – minutes])
- Total = [Total minutes]÷60
- Decimal hours = [Total minutes]÷60
- Total seconds = [Total minutes]×60
Formula
Total minutes = (h₁ × 60 + m₁) ± (h₂ × 60 + m₂) ± (h₃ × 60 + m₃)Hours = floor(total ÷ 60); minutes = total mod 60Worked example
Inputs — Duration 1 – hours: 3; Duration 1 – minutes: 45; Then: Add; Duration 2 – hours: 2; Duration 2 – minutes: 30; Then: Add; Duration 3 – hours: 0; Duration 3 – minutes: 50.
Results — Total minutes = 425; Total = 7 h 5 min; Decimal hours = 7.08; Total seconds = 25,500.
Frequently asked questions
What is 3 h 45 min + 2 h 30 min?
6 h 15 min.
How do I add hours and minutes?
Add the minutes; every 60 minutes becomes one hour; then add the hours.
How do I subtract hours and minutes?
Convert both to minutes, subtract, then convert back.
What formula does the Hours and Minutes Calculator use?
Total minutes = (h₁ × 60 + m₁) ± (h₂ × 60 + m₂) ± (h₃ × 60 + m₃).