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Compute the duration between two times of day, even across midnight.
Compute the duration between two times of day, even across midnight.
Enter values above and click Calculate — results will appear here with the formula explained.
Clock arithmetic isn't ordinary subtraction because hours wrap at 24. From 22:00 to 06:00 is not negative sixteen hours but eight — the overnight wrap is the single most common duration error.
Expressing results in decimal hours bridges to payroll and billing systems, where 7¾ hours must be entered as 7.75. Keep the minutes view for humans and decimals for spreadsheets.
The 24-hour format eliminates a whole error class: 12-hour times need AM/PM disambiguation (is 12:00 midnight or noon? midnight is 00:00, noon is 12:00) while 08:45 and 16:15 sort, subtract and compare unambiguously. Teams spanning time zones should standardize on 24-hour plus explicit zone rather than converting casually.
Break deductions follow wage-and-hour logic: unpaid meal breaks (typically 30–60 min) subtract from compensable time, while short paid rest breaks (10–20 min) usually don't. Enter only genuinely unpaid minutes — deducting paid breaks underpays staff and misstates project costs the same direction every time.
Overnight spans need the wrap rule stated plainly: if end < start, add 1,440 minutes before subtracting. Night shifts, red-eyes, hospital rotations and server maintenance windows all live here; forgetting the wrap turns an 8-hour night into a −16-hour impossibility that spreadsheets happily propagate.
Beyond-a-day spans belong elsewhere: this tool handles time-of-day intervals, while multi-day durations need the date-difference calculator (dates) plus leftover minutes here. Chaining them — dates for days, this for the remainder — covers any span without the month-length ambiguity of mixed approaches.
Compute the duration between two times of day, even across midnight. Formula: minutes = (end − start). Example: 22:00 to 06:00 minus a 45-minute break: wraps to 480 minutes, less 45, giving 7 h 15 min — 7.25 decimal hours.
Clock arithmetic isn't ordinary subtraction because hours wrap at 24. From 22:00 to 06:00 is not negative sixteen hours but eight — the overnight wrap is the single most common duration error.
Expressing results in decimal hours bridges to payroll and billing systems, where 7¾ hours must be entered as 7.75. Keep the minutes view for humans and decimals for spreadsheets.
The 24-hour format eliminates a whole error class: 12-hour times need AM/PM disambiguation (is 12:00 midnight or noon? midnight is 00:00, noon is 12:00) while 08:45 and 16:15 sort, subtract and compare unambiguously. Teams spanning time zones should standardize on 24-hour plus explicit zone rather than converting casually.
Break deductions follow wage-and-hour logic: unpaid meal breaks (typically 30–60 min) subtract from compensable time, while short paid rest breaks (10–20 min) usually don't. Enter only genuinely unpaid minutes — deducting paid breaks underpays staff and misstates project costs the same direction every time.
Overnight spans need the wrap rule stated plainly: if end < start, add 1,440 minutes before subtracting. Night shifts, red-eyes, hospital rotations and server maintenance windows all live here; forgetting the wrap turns an 8-hour night into a −16-hour impossibility that spreadsheets happily propagate.
Beyond-a-day spans belong elsewhere: this tool handles time-of-day intervals, while multi-day durations need the date-difference calculator (dates) plus leftover minutes here. Chaining them — dates for days, this for the remainder — covers any span without the month-length ambiguity of mixed approaches.
22:00 to 06:00 minus a 45-minute break: wraps to 480 minutes, less 45, giving 7 h 15 min — 7.25 decimal hours. A 08:45–16:15 shift with 30 unpaid minutes is 450 − 30 = 420 minutes = 7.0 hours exactly.
Formulas are standard public references (see our methodology). External standards are cited in the text where they apply.
Last reviewed: September 2026 · Report an error