This calculator converts a time written as hours, minutes and seconds into one number: total seconds, total minutes and decimal hours. It is the step you need before multiplying a duration by a rate or adding times on a spreadsheet.
Formula
An hour has 3,600 seconds and a minute has 60, so total seconds = h × 3600 + m × 60 + s. Total minutes = seconds ÷ 60 and decimal hours = seconds ÷ 3600.
- h, m, s: the hours, minutes and seconds of the duration
Worked Example
2 h 45 min 30 s.
- 2 × 3600 = 7,200 s; 45 × 60 = 2,700 s; plus 30 s
- Total = 7,200 + 2,700 + 30 = 9,930 s
- Minutes = 9,930 ÷ 60 = 165.50 min
- Hours = 9,930 ÷ 3600 = 2.7583 h
Limits and common mistakes
- Decimal hours are not clock time: 2.7583 h is 2 h 45.5 min, not 2:75.
- Minutes or seconds above 59 are fine; the sum still works (90 min = 1.5 h).
- For pay or billing, round only the final figure, not each part.
Formula used
in h | Hours | h | 2 | 0 in m | Minutes | min | 45 | 0 in s | Seconds | s | 30 | 0 out sec | Total seconds | s | h * 3600 + m * 60 + s | 0 out mins | Total minutes | min | sec / 60 | 2 out hrs | Decimal hours | h | sec / 3600 | 4
Each line is one input (in, sel, list) or one result (out: label, unit, formula, decimals). How the calculators work
Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.