Add clock-style and decimal durations
The separator changes the meaning, so every input keeps its format label.
The two inputs
| Input | Interpretation | Minutes |
|---|---|---|
| 07:30 | 7 hours 30 minutes | 450 |
| 7.30 h | 7 hours plus 0.30 hour | 438 |
The checked sum
Multiplying the decimal fraction 0.30 by 60 gives 18 minutes. Reading it as 30 minutes would add twelve minutes that the value does not contain. The two visible inputs therefore do not add to fifteen hours.
Preserve meaning when copying
Use separate column headings for clock-style duration and decimal hours, or choose one format for the whole exported view. A spreadsheet’s automatic cell formatting may display a duration differently. Check the underlying value and the unit before replacing the original record with a formatted copy.
Use this example
Open related toolFrequently asked questions
Why do similar-looking inputs contribute different minutes?
07:30 is 450 minutes, while 7.30 decimal hours is 438 minutes. Their 888-minute sum is 14:48.
Can I fix the difference just by changing a display separator?
No. First determine the source format, then convert its value. Relabeling 7.30 as 7:30 changes the amount of time.
Sources and method
- NIST SP 330, Section 4, Table 8Time-unit definitions only; not a payroll authority or product endorsement.
- Original worked calculationSynthetic example data, explicit input rules and direct integer-minute arithmetic.
Keep going
Add work hours
Add multiple work durations in hours and minutes or decimals, keep totals above 24 hours, and apply an optional personal threshold.
Hours and decimal hours: why 7.30 is not 7:30
Understand hours-and-minutes and decimal notation, convert either way, and avoid losing minutes by adding rounded displays.
Worked time-card examples
Browse twelve checked examples of split shifts, overnight breaks, date boundaries, decimal durations and file review.