Clock span
Time of Day Duration
Hours and minutes from one clock time to another, wrapping midnight.
Time of day duration
Enter start and end clock times.
Time of day duration measures how many hours and minutes sit between two clock faces on a repeating 24-hour circle. You enter a start time and an end time. If the end is earlier on the clock than the start, the span is treated as crossing midnight and twenty-four hours are added before the result. There is no calendar date, no hourly rate, and the break field defaults to zero so a pure clock span is not quietly shortened by a lunch deduction.
Clock faces, not datetimes
A datetime subtracts two full timestamps, each with a date. This page ignores the date. 22:00 to 06:00 is eight hours whether those faces belong to Monday night or Saturday night. That is the right model for a night radio shift, a bakery oven window, or “how long from now until 3:00 PM” when you only have wall clocks. It is the wrong model for “how long from 3 March 09:00 to 5 March 09:00,” which needs dated hours.
The hours calculator is built for punch-style shifts that may include an unpaid break and a dated mental model. Date-only distance (how many calendar days) belongs on date-duration tools under the date tools hub. Keep this URL when both ends are times of day and the calendar is irrelevant.
Because there is no date, DST spring-forward days are not modeled. A 01:30 to 03:30 span is always two hours here even if that civil night skipped an hour in a zone that observes DST. If the legal length of a shift on a transition night matters, use dated timestamps in a zone-aware hours tool instead.
Overnight wrap
When end minus start is negative, the calculator adds 24 hours. 23:15 to 07:45 becomes 8 hours 30 minutes, not a negative number. The result labels the span as overnight. Equal start and end is a zero-length span on the same face, not a 24-hour day; if you meant a full rotation, enter 24:00 as a convention only if the control allows it, or use 00:00 the next morning with wrap from 00:00.
Wrap is a circle, not a guess about which calendar morning. It does not know whether the person slept. It only knows two readings on a 24-hour dial. Document that assumption on a timesheet if a supervisor might read “overnight” as a claim about lodging or a second date.
Split duties that return to the same clock twice (morning block, evening block) should be calculated as two spans and added. A single wrap from 09:00 to 09:00 the next thought-of morning is zero if you enter the same face twice. Two fields cannot encode a 24-hour on-call day without a date.
Hours, minutes, and decimal hours
Output lists hours and minutes worked plus decimal hours (minutes divided by 60). Decimal form is what many spreadsheets and invoice templates expect. 1 hour 15 minutes is 1.25, not 1.15. Mixing the two notations is a common payroll error. Copy the decimal line when the receiving form has a single number field.
Seconds are not in the time inputs (step is one minute). If you need second precision, this is the wrong instrument. Live elapsed timing while a task is running belongs on a stopwatch; paste the final reading back only if you must store clock faces.
The time calculator adds or subtracts a duration onto a baseline clock. Use that when the question is “what time is it after 3 hours 40 minutes,” not “how long between these two faces.”
Break minutes stay at zero unless you mean it
A break field exists because this control shares a layout with shift tools. On this page it defaults to zero. Leave it there for a raw clock span. If you type 30, those minutes are subtracted, which silently turns a duration tool into a paid-hours tool. That mix is confusing on invoices. For hours times a rate after a lunch, use the billable calculator instead.
Unpaid lunch policies do not belong in a duration answer unless the questioner asked for net time. Classroom “how long is this exam window” should stay gross. Night-club “doors at 21:00, last entry 02:00” should stay gross. Net time is a billing or labor question.
Worked clock examples
A hospital porter walks 19:40 to 04:10. Enter those faces. Wrap adds 24 hours to the negative difference, then the display shows 8 hours 30 minutes and 8.50 decimal hours, marked overnight. No date is required even if the roster sheet shows two calendar days.
A teacher asks how long from the 08:15 bell to the 14:05 dismissal. Same-day faces, no wrap, result 5 hours 50 minutes. If a 25-minute recess should be excluded, that is a policy choice: either subtract later on paper or fill the break field knowing you have left pure duration behind.
A podcast producer schedules a 22:30 recording that must end by 00:15. The wrap result is 1 hour 45 minutes. That number is the tape budget. It is not the producer’s pay and not a timezone conversion for a guest abroad.
When another tool is a better fit
Two timestamps with dates, possibly spanning several midnights, belong on dated hours tools. A count of calendar days, weeks, or months belongs on date math. Money belongs on the billable page. IANA cities belong on difference or world-clock pages. This page should stay boring: two clocks, one span, optional wrap.
AM/PM mistakes dominate errors. 7:00 to 7:00 can mean zero minutes or twelve hours depending on whether both faces were meant as 07:00 and 19:00. Prefer 24-hour entry. If the source used twelve-hour labels, convert on paper before typing.
Planning a week of such windows still benefits from a printed grid: monthly calendars show which nights exist in 2026 without turning this duration tool into a calendar.
Related tools
Dated punch math: hours calculator. Add a duration to a clock: time calculator. Other clocks and timers: time tools hub.
Frequently asked questions
What clock span does this page measure between two times?
It measures hours and minutes between two clock faces on a 24-hour circle, plus the same length as decimal hours. Calendar dates are ignored. The result is a duration, not a new clock time and not a currency amount. Overnight wrap applies only when the end face is earlier than the start face.
How does overnight wrap work when the end is earlier?
A negative difference has 24 hours added, so 22:00 to 06:00 becomes eight hours and is labeled overnight. The page does not know which calendar morning that is. Equal start and end is a zero span, not a 24-hour shift. Split blocks that return to the same face should be entered as two separate spans.
Why should unpaid breaks be left at zero here?
The break field is shared with shift layouts and defaults to zero on this page so a raw clock span is not shortened. Typing 30 minutes turns the tool into net paid time, which confuses duration questions such as exam windows or door times. Use the billable calculator when lunch and a rate are part of the question.
Is this the same as subtracting two full calendar datetimes?
No. Datetime subtraction uses dates and can span several midnights. This page uses only clock faces, so Tuesday 22:00 to Wednesday 06:00 looks the same as any other 22:00 to 06:00. Multi-day dated hours belong on the hours calculator. Calendar-day counts belong on date-duration tools.
When should a night shift use this duration tool?
Use it when both ends are wall-clock times and you do not need a date, a zone, or a dollar total. Hospital nights, bakeries, and late recordings fit. If the shift falls on a DST spring-forward night and legal hours matter, switch to zone-aware dated timestamps, because this circle always treats 01:30 to 03:30 as two hours.
How are hours and minutes shown after a wrap?
The display lists hours and minutes plus decimal hours from total minutes divided by 60. One hour 15 minutes is 1.25, not 1.15. Seconds are not accepted. Copy the decimal line into spreadsheets that want a single number. The overnight label is informational; it does not add extra paid time by itself.