Hours and minutes do not add like money. Sixty minutes make an hour, not a hundred, so a pocket calculator or the Windows calculator gets every timesheet total wrong unless you convert each line first. DeskCalc's time calculator does the counting in hours and minutes for you, on the same running tape you use for everything else.
Why a normal calculator gets hours wrong
A five-day week, typed as hours.minutes:
| Day | Worked | Normal calculator | DeskCalc time calculator |
|---|---|---|---|
| Mon | 7 h 45 min | 7.45 | 07:45 |
| Tue | 8 h 30 min | 8.30 | 08:30 |
| Wed | 8 h 15 min | 8.15 | 08:15 |
| Thu | 7 h 50 min | 7.50 | 07:50 |
| Fri | 6 h 40 min | 6.40 | 06:40 |
| Total | 39 h 00 min | 37.80 ✗ | 39:00 ✓ |
The normal calculator says 37.80 for a week of exactly 39 hours — it treats 45 minutes as 0.45 of an hour. The time calculator carries every 60 minutes into a full hour.
How to add hours and minutes in DeskCalc
1. Switch on the time calculator
Choose Functions ▸ Time calculator, or press Ctrl + F9. The same command switches it off again when you are back to normal figures.
2. Type hours, the decimal key, then minutes
For 7 hours 45 minutes type 7.45 on the numeric keypad — DeskCalc shows 07:45. For minutes only, start with a zero: 30 minutes is 0.30. Minutes go from 00 to 59.
3. Add each day, read the total
Press + after every entry, exactly as on an adding machine, and take the total when you are done. Totals keep counting past 24 hours, so a week shows as 39:00 and a month as 162:30 — there is no rollover to a new day.
4. Label the lines
Add a comment to any line — the weekday, a job number, an employee's name. The tape then reads like a timesheet, not like a column of digits.
5. Fix a wrong entry without starting over
Typed 8:15 instead of 8:45 on Wednesday? Click the line on the tape, correct it, and every total below it is recalculated. On a paper tape you would run the whole week again.
6. Keep the record
Print the tape on your office printer, save it as a PDF, or save the calculation and open it again next week. The figures stay on your PC — DeskCalc needs no account and no internet connection.
Start, end and breaks
Subtraction works the same way. To get the hours worked from a start and an end time, take the end time, subtract the start time and the break:
Use the 24-hour clock for times after noon (5:15 pm is 17.15). If a result is negative — fewer hours than planned, for example — DeskCalc shows it with a minus sign, such as −00:15.
Hours and minutes to decimal hours
Payroll and invoices usually want decimal hours: 39 hours 45 minutes is 39.75 hours. The rule is minutes ÷ 60. The common values:
| Minutes | Decimal hours |
|---|---|
| 6 | 0.10 |
| 10 | 0.17 |
| 15 | 0.25 |
| 20 | 0.33 |
| 30 | 0.50 |
| 40 | 0.67 |
| 45 | 0.75 |
| 50 | 0.83 |
So a week of 38:45 is 38.75 hours, and at $24.00 an hour that is $930.00. Do the pay calculation with the time calculator switched off.
What it is — and what it is not
The time calculator is a calculator: it adds and subtracts hours and minutes on a tape you can check, label and keep. It is the quick way to total a timesheet, check an employee's hours, add up billable time or the minutes on a set of recordings.
It is not a time clock. It does not record when people start work, apply overtime rules or run payroll. If you need that, you need time-tracking software; if you need to add up the hours someone hands you, this is faster.
Already using DeskCalc? Input rules, minutes and seconds, and answers to common questions are in the time calculator documentation.
Try the time calculator
The time calculator is part of DeskCalc — the Windows adding machine with the tape on screen. The trial is free for 31 days with every feature; after that it is a one-time licence, no subscription.