Time Duration Calculator

What this calculator does

This calculator measures the elapsed time between two specific points in time. Use Time only mode to calculate duration between two clock times on the same day — or across midnight for night shifts. Use Date & time mode when the period spans multiple days and you need a calendar-aware breakdown. Both modes support optional break subtraction to give you gross and net durations.

How to use it

1. Choose a mode: Time only (for clock times) or Date & time (for multi-day periods).
2. Enter your start and end times. For cross-midnight shifts, check the “Crosses midnight” box.
3. Optionally enter a break duration in hours and minutes to subtract from the total.
4. Click Calculate to see gross duration, net duration, decimal hours, total minutes, and total seconds.

Calculate elapsed time — examples

• Meeting: 9:15 AM to 11:45 AM → gross 2h 30m (2.5 decimal hours, 150 total minutes)
• Work shift with lunch: 8:30 to 17:00 with 30-min break → gross 8h 30m, net 8h 00m (8.0 decimal hours)
• Night shift: 22:30 to 06:15 (crosses midnight) → gross 7h 45m (7.75 decimal hours)

Decimal hours

Decimal hours express duration as a single number rather than hours and minutes. To convert manually: divide the minutes by 60 and add to the hours. For example, 8 hours 30 minutes = 8 + (30 ÷ 60) = 8.5 decimal hours. This format is standard for payroll, billing, and time-tracking systems that require a single numeric value.

Gross vs. net duration

Gross duration is the total elapsed time from start to end with no deductions. Net duration is the gross minus any break time entered. If no break is entered, gross and net are identical. For payroll purposes, gross represents clock-in to clock-out while net represents actual paid working time.

Date & time mode — calendar breakdown

When you need to calculate duration between two full date/times, the Date & time mode returns a calendar-aware breakdown: years, months, days, hours, minutes, and seconds. The month decomposition uses actual calendar boundaries, so one month means going from (say) March 15 to April 15 — not adding exactly 30 days. Leap years are accounted for automatically in the total-days count.

Assumptions and limitations

• Times are entered in 24-hour (HH:MM) format. 9:00 AM = 09:00, 1:30 PM = 13:30.
• Dates are interpreted in your local time zone. Daylight saving time transitions may shift totals spanning a clock change by ±1 hour.
• The break must be strictly less than the gross duration — entering a break equal to or longer than the total returns an error.
• Time zones are not converted — start and end are treated as the same local time zone.