Time Calculator
Four time problems in one place: add durations, measure a gap, count working days, convert units.
Result
What this calculator does
Time arithmetic is the kind of thing that looks easy and then quietly goes wrong. Adding 2h 45m to 3h 30m in your head is fine; adding up a week of timesheet entries is not. Counting the working days in a project that crosses two public holidays and a weekend is worse again.
This calculator covers the four problems that come up most often. Add or subtract two durations. Measure the exact gap between two dates and times, including across daylight-saving changes. Count the working days in a period, with the option to treat Saturday as a working day. And convert any amount of time between seconds, minutes, hours, days and weeks.
How to use it
- Pick the tab for your question. Add or subtract handles timesheet-style sums.
- For Between two dates, set both a date and a time — the field opens your device's picker.
- On Working days, both the first and last day are counted. Add the number of public holidays falling inside the period so they can be deducted.
- Tick the Saturday box if your working week runs Saturday to Thursday rather than Monday to Friday.
The formula
Durations total_seconds = h × 3600 + m × 60 + s
Between dates difference = end_timestamp − start_timestamp
Working days count each day from start to end, skip Sundays
(and Saturdays unless marked as a working day),
then subtract public holidays
Timestamps carry the time-zone and daylight-saving rules of your own device, so a period spanning a clock change comes out right.
Worked examples
| Scenario | What you enter | Result |
|---|---|---|
| Two shifts of 7h 45m and 6h 30m | Add | 14:15:00 — 14.25 hours |
| A 9h 15m day minus a 45m lunch | Subtract | 08:30:00 |
| Flight leaving 22:40 on 3 May, landing 06:15 on 4 May | Between | 7 hours 35 minutes |
| A project from 1 to 30 September with 2 public holidays | Working days | 20 working days, 160 hours |
| How many hours in 3.5 days | Convert | 84 hours |
Frequently asked questions
Convert everything to a single unit first — seconds is easiest — then add, then convert back. The mistake people make is treating minutes as decimals: 1h 30m is 1.5 hours, not 1.30. This calculator does the conversion internally and reports the answer both as hh:mm:ss and as a decimal number of hours, which is what most payroll systems want.
Yes. A project running Monday to Friday counts as five working days, not four. This is the convention used in most project plans and contracts, but it is not universal — some systems count elapsed days instead. If you need the exclusive count, subtract one from the result.
Enter how many fall inside your period and they are deducted from the working-day total. The calculator does not know your country's holiday calendar, because holidays vary by country, emirate, state and sometimes by employer. Checking your own official calendar and typing the number keeps the answer right wherever you are.
Because Monday-to-Friday is not universal. Across much of the Gulf and South Asia the working week runs Saturday to Thursday, or Sunday to Thursday, with Friday as the day of rest. Ticking the box counts Saturday as a working day and leaves Sunday off, which covers the most common of those patterns.
Yes, for the “between two dates” calculation. It works from real timestamps in your device's time zone, so a period that crosses a clock change comes out as the true elapsed time — a night where the clocks go forward is genuinely 23 hours long, and that is what you will see.
It works well for adding two entries at a time, and the decimal-hours figure is what payroll systems usually expect. For a full week, add entries in pairs, or use the convert tab to turn each day into decimal hours and total them. The History button keeps your last ten results, which helps when you are working through a stack of days.
The calendar figure is how people speak — “2 years, 3 months, 5 days”. The total-days figure is the raw count of days in the same period. Calendar months have different lengths, so the two cannot be converted into each other with a fixed multiplier. Both are shown because different forms and contracts ask for different ones.
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