How to use this calculator
- Enter or choose operation.
- Add a grade and credits for each course; leave unused rows blank.
- The result updates as you type. Use Copy result or Share to keep it.
Method
Seconds = 86,400 × days + 3,600 × hours + 60 × minutes + seconds for each duration; add or subtract, then split back into days, hours, minutes and seconds.
- 86,400
- seconds in a day
- 3,600
- seconds in an hour
Worked example
- First: 86,400 + 7,200 + 1,800 = 95,400 s.
- Second: 82,800 + 2,700 + 30 = 85,530 s.
- Sum: 180,930 s = 2 days (172,800 s) + 2 h (7,200 s) + 15 min (900 s) + 30 s.
1 day 2 h 30 min plus 23 h 45 min 30 s is 2 days 2 h 15 min 30 s, or about 50.26 hours.
What the result means
Decimal hours are what timesheets and invoices usually need: 15 minutes is 0.25 h, 30 minutes 0.5 h and 45 minutes 0.75 h. A negative result means the second duration is longer than the first.
Assumptions and limits
- A day is exactly 24 hours (durations, not calendar days across a daylight-saving change).
- To find the time between two clock times, use the Hours Calculator.
Questions
How do I convert minutes to decimal hours?
Divide by 60. For example 45 minutes ÷ 60 = 0.75 hours, so 7 h 45 min is 7.75 hours.
Can I enter 90 minutes?
Yes. Any field can exceed its usual range; the result is normalised to 1 h 30 min.