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If the end time is earlier than (or equal to) the start time, the tool assumes it ran past midnight and adds 24 hours, labeling it “next day”.
A time duration calculator does one job extremely well: it performs arithmetic on hours, minutes, and seconds. Subtract a start time from an end time to get a shift length, add two durations to total a project, or sum a whole list of durations to reconcile a timesheet. It sounds simple, but doing it by hand is famously error-prone β 60 minutes to an hour and 60 seconds to a minute means ordinary decimal addition does not work, and one careless carry ruins the result.
The Time Duration Calculator on fisthost.com/tools handles all of it in your browser: duration between two times (with overnight shifts handled correctly), add/subtract mode for combining durations, a list-sum mode for totals, and outputs in hours-minutes-seconds, decimal hours, total minutes, and total seconds. No signup, no downloads, everything client-side.
Enter a start time and an end time, and the tool returns the elapsed duration. The key detail it gets right is the overnight case: if the end time is earlier than or equal to the start time, the tool assumes the period crossed midnight and adds 24 hours, labeling the result as continuing into the next day. So a shift from 22:00 to 06:00 correctly returns 8 hours, not a negative number.
A support shift runs from 21:45 to 05:30. Since 05:30 β€ 21:45, add 24 hours: (24:00 β 21:45) + 05:30 = 2:15 + 5:30 = 7 hours 45 minutes.
In add/subtract mode, the inputs are durations, not clock times β the tool keeps the two modes visually separate so you never mix them up. Add two or more durations together, or subtract one from another:
This is the mode freelancers use to combine billable blocks and managers use to total team hours.
Paste a list of durations, one per line, and the tool returns the grand total. Typical uses:
The tool tolerates flexible formats (e.g. "1:30", "1h 30m", "90m"), skips blank lines, and reports if any line could not be parsed.
Every result is also shown in converted units, because different systems want different formats:
| Format | How it is computed | Example: 2h 30m |
|---|---|---|
| Decimal hours | h + m/60 + s/3600 | 2.5 hours |
| Total minutes | hΓ60 + m (+ s/60) | 150 minutes |
| Total seconds | hΓ3600 + mΓ60 + s | 9,000 seconds |
Decimal hours are what payroll and invoicing systems expect: 2h 30m becomes 2.5h, 45 minutes becomes 0.75h. The tool computes these exactly, so you never have to remember that 20 minutes is 0.333 hours.
Time is not decimal, and that is the whole problem. A few classic mistakes:
Healthcare staff, security guards, and factory workers regularly work across midnight. The overnight-aware between-times mode gives the exact shift length, and list-sum mode totals the week in one paste.
Track each client session as a duration, paste the list at month end, and read off the decimal-hours total your invoice needs. Pair it with the Invoice Generator to turn hours into a professional bill.
Add estimated durations for project phases to sanity-check a timeline: 3h 20m + 5h 45m + 2h 10m = 11h 15m of work, which is more than one working day β the estimate needs revisiting.
Sum workout sessions or Pomodoro blocks to see your true weekly investment. Speaking of which, the Pomodoro Timer is a great companion for timed focus sessions.
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Yes. If the end time is earlier than or equal to the start time, the calculator adds 24 hours and labels the result as continuing into the next day.
Between-times mode takes two clock times and returns the elapsed duration. Add/subtract and list-sum modes take durations (lengths of time) and combine them. The interface keeps them visually separate so inputs are never ambiguous.
Flexible ones: "1:30", "1h 30m", "90m", "5400s" and similar are all understood. Blank lines are skipped, and unparseable lines are reported.
Payroll software, invoicing tools, and spreadsheets expect hours as decimals β 2h 30m = 2.5h. The calculator shows this alongside the H:M:S form.
No. All calculations happen locally in your browser; nothing you type ever leaves your device.
Explore the rest of the date-and-time collection: the Date Duration Calculator for days between dates, the Working Days Calculator for business-day math, the Pomodoro Timer for focused work sessions, and the Countdown Timer for upcoming events.
Whether it is a timesheet app, a portfolio, or a full online store, every project needs a home. FistHost offers shared hosting from $0.99/month with a free domain on annual plans β everything you need to get online today, backed by support that actually helps.
Spreadsheet programs store times as fractions of a day, which confuses almost everyone the first time. In a spreadsheet, 6:00 PM is stored as 0.75, and subtracting 9:00 AM from it gives 0.375 β which you must then reformat as a duration to read as 9 hours. Overnight shifts need clumsy IF formulas, and adding a column of durations requires custom number formats that break the moment someone types "90 minutes" as text. A dedicated calculator skips all of that: you type times and durations the way humans write them, and it handles midnight crossings, carry-overs, and unit conversions automatically.
| Duration | Decimal hours | Total minutes |
|---|---|---|
| 15 minutes | 0.25 h | 15 |
| 30 minutes | 0.5 h | 30 |
| 45 minutes | 0.75 h | 45 |
| 1 hour 20 minutes | 1.333 h | 80 |
| 2 hours 45 minutes | 2.75 h | 165 |
| 7 hours 30 minutes | 7.5 h | 450 |
Keep this table in mind when filling timesheets: entering 7.3 hours instead of 7.5 for a 7h30m day silently under-reports 12 minutes of work.
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