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Time • Calculator

Time Calculator

Calculate durations between times (with cross-midnight and break handling), plus add and subtract time durations. Payroll rounding to quarter, tenth or hundredth hour.

Direct Answer

The time calculator adds or subtracts multiple time intervals by normalizing them into base seconds, performing standard arithmetic, and converting the result back into days, hours, minutes, and seconds, or decimal hours.

Start time

End time

Duration

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Decimal hours

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Payroll

If end < start with no dates, we assume next day (cross-midnight). If equal, duration is 0 (enter 24h explicitly for a full day). With dates, exact difference is used. Break is subtracted. Payroll rounding is for display — decimal hours remain exact.

How to use

  1. 1For Duration: enter start and end times (12h AM/PM or 24h) with optional dates. If end ≤ start without dates, we assume next day.
  2. 2Subtract a break (minutes) and choose payroll rounding if needed. Result shows HH:MM:SS, decimal hours, minutes and days.
  3. 3For Add & Subtract: enter any number of H:M:S durations and see the total (use negative rows or delete to subtract).

How it works

Duration = End − Start (+24h if cross-midnight) − Break • Decimal = h + m/60 + s/3600 • Quarter = round(h×4)/4
VariableNameMeaning & Example
HHoursWhole number of elapsed 60-minute blocks (14 hrs)
MMinutesRemaining 60-second intervals (45 mins)
SSecondsBase unit of duration (30 secs)

When dates are given, we compute exact datetime difference. Without dates, end ≤ start adds 24h. Decimal hours convert to payroll: quarter (15m) and tenth (6m). Add & Subtract sums each duration’s seconds.

Examples

09:00 to 17:30 minus 60m break

Raw 8.5h −1h break = 7.5h • 450 minutes • 27,000 seconds.

07:30:00 • 7.5h

22:00 to 06:00 (next day)

Cross-midnight: (24−22)+6 = 8h.

08:00:00 • 8.0h

About

The Time Calculator handles the two operations people most often need: calculating the duration between two clock times, and adding or subtracting multiple time intervals. For durations, enter start and end times with an optional break, and it returns the result in hours, minutes, seconds, decimal hours, and days, including overnight-shift handling and payroll rounding. The add-and-subtract mode keeps a running total of many H:M:S entries. Shift workers, project managers, and students use it for timecards, elapsed-time problems, and scheduling that mixes hours and minutes across the day.

Frequently asked questions

Why did my 09:00–09:00 show 24 hours?
Without dates, equal times assume a full 24h wrap. Add explicit dates if you meant zero.
What is payroll rounding?
Quarter rounds to 0.25h (15 min) and tenth to 0.1h (6 min), common for timecards. Exact decimal is still shown.
Can I add many durations?
Yes — switch to Add & Subtract and add as many H:M:S rows as needed.
How do I add two time durations together?
Add seconds first, carrying over 1 minute for every 60 seconds. Then add minutes, carrying over 1 hour for every 60 minutes. Finally, sum the hours.
How do you convert clock time to total seconds?
Multiply hours by 3,600, multiply minutes by 60, and add the remaining seconds: Total Seconds = (Hours × 3600) + (Minutes × 60) + Seconds.
How do you find the duration between two timestamps?
Convert both times to minutes or seconds from midnight, subtract the earlier time from the later time, and convert the difference back to hours and minutes.

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