Time Duration Calculator

1. 01Enter the start and end timePick both times using the time pickers.
2. 02Read the durationThe result shows hours and minutes, plus the equivalent in decimal hours (useful for timesheets and billing).
3. 03Check the overnight note if it appearsIf the end time is earlier than the start time, this tool treats it as an overnight span ending the next day, and says so explicitly.

• Calculating work shift lengthFind how many hours a shift lasted from clock-in to clock-out time, including overnight shifts.
• Converting a time span to decimal hours for a timesheetGet the decimal-hours equivalent (e.g. 8h 30m = 8.5 hours) for payroll or billing systems that expect decimal values.
• Planning a meeting or event durationQuickly check how long a scheduled block of time actually is, without doing the subtraction by hand.

• A daytime span9:00 AM to 5:30 PM is 8 hours 30 minutes (8.5 decimal hours).
• An overnight shift10:00 PM to 6:00 AM is 8 hours — this tool detects that the end time is earlier than the start time and treats it as spanning into the next day.
• Identical start and end timeIf the start and end time are the same, the duration is 0 — not 24 hours — since there is no way to know from clock times alone whether a full day was intended.

This tool works entirely with hours and minutes on a 24-hour clock — it does not know or use any calendar date, timezone, or daylight-saving-time information. That keeps the math simple and unambiguous: it always measures the distance between two times of day, the same way everywhere.

If the end time is earlier than the start time (for example, start 22:00, end 06:00), this tool assumes the end time falls on the next day and adds 24 hours before calculating the difference — the standard interpretation for a work-shift or overnight-duration calculation. This assumption is always shown explicitly in the result, never applied silently.

If you enter the same time for both start and end, the result is 0 minutes. A full 24-hour span is a real possibility in some contexts (like an all-day shift), but clock times alone cannot distinguish that from a simple "no elapsed time" case, so this tool uses the more common and less surprising interpretation.

Does this account for daylight saving time?

No — this tool intentionally works with plain clock times, not real calendar timestamps, so daylight saving time and timezones never enter the calculation. If you need duration between two specific real-world timestamps (crossing a DST change, for example), the result may differ from what a full date-and-time calculation would show.

How does the calculator handle an overnight shift?

If the end time is earlier than the start time, it is treated as falling on the next day (for example, 11 PM to 7 AM is 8 hours), and this tool always shows a note when that assumption is applied.

What are decimal hours, and why are they shown?

Decimal hours express a duration as a single number (like 8.5 instead of 8h 30m) — commonly needed for timesheets, payroll, or billing systems that expect decimal input.

Is my data saved?

No. Everything is calculated in your browser; nothing is sent to a server.