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Time Duration Calculator

Compute the time elapsed between two clock times, even across midnight.

Results

Hours
7.75
Minutes
465.00

How to use this calculator

  1. Enter the start time using a 24‑hour clock (for example, 9:30 as 9 and 30, or 21:00 as 21 and 0).
  2. Enter the end time you want to measure up to, also in 24‑hour format.
  3. We convert both times to minutes since midnight, subtract, and adjust if the end time falls after midnight.
  4. Review the elapsed hours and minutes between the two times.
  5. If your period includes unpaid breaks, subtract their duration manually from the result.

Inputs explained

Start time
The clock time when the period begins, expressed as hour (0–23) and minute (0–59) on a 24‑hour clock. For example, 7:45 AM = 7 and 45; 7:45 PM = 19 and 45.
End time
The clock time when the period ends, also on a 24‑hour clock. If you enter a time earlier than the start time, the calculator assumes the period crossed midnight into the next day.

How it works

We interpret your start and end times as 24‑hour clock values (0–23 hours and 0–59 minutes).

We convert both times into minutes since midnight: totalMinutes = hour × 60 + minute.

We subtract the start total from the end total to get a raw difference in minutes.

If the raw difference is negative (meaning the end time appears earlier than the start time), we assume the end time is on the following day and add 24 hours’ worth of minutes.

We then convert the final difference back into hours and minutes and present both values to you.

Formula

StartTotal = startHour × 60 + startMinute\nEndTotal = endHour × 60 + endMinute\nRawDiff = EndTotal − StartTotal\nIf RawDiff < 0, RawDiff += 24 × 60\nHours = floor(RawDiff ÷ 60)\nMinutes = RawDiff mod 60

When to use it

  • Checking shift durations for payroll or invoicing when all you have is a clock‑in and clock‑out time.
  • Timing workouts, events, or study sessions, including those that run past midnight.
  • Quickly computing elapsed time for travel, meetings, or overnight tasks without a stopwatch.
  • Sanity‑checking logs from time trackers or manual timesheets.

Tips & cautions

  • Use 24‑hour times to avoid AM/PM confusion (for example, 1 PM = 13:00, 11 PM = 23:00).
  • If your work or session includes multiple breaks, subtract the total break time from the duration the calculator returns.
  • For multi‑day spans, break the period into daily chunks or use a date‑based duration tool in addition to this time‑of‑day calculator.
  • Be cautious around daylight saving time changes—if your shift spans a clock change, manually adjust for the gained or lost hour.
  • No built‑in break handling—any unpaid or off‑task time must be subtracted manually from the calculated duration.
  • Does not explicitly model daylight saving time transitions; you must adjust for DST if a period crosses a clock change.
  • Treats start and end as times within a 24‑hour window and assumes at most a single midnight crossover; not intended for multi‑day spans.

Worked examples

Standard workday: 9:30 to 17:15

  • Start = 9:30 → 9 × 60 + 30 = 570 minutes.
  • End = 17:15 → 17 × 60 + 15 = 1,035 minutes.
  • RawDiff = 1,035 − 570 = 465 minutes → 7 hours and 45 minutes (7.75 hours).

Overnight shift: 22:15 to 01:45

  • Start = 22:15 → 22 × 60 + 15 = 1,335 minutes.
  • End = 1:45 → 1 × 60 + 45 = 105 minutes.
  • RawDiff = 105 − 1,335 = −1,230; add 1,440 minutes for midnight crossover → 210 minutes.
  • Result = 3 hours and 30 minutes (3.5 hours).

Deep dive

This time duration calculator converts start and end times into elapsed hours and minutes, even when your shift or event crosses midnight.

Enter 24‑hour start and end times to get an instant duration for payroll, billing, workouts, or scheduling without manual clock math.

Perfect for anyone who needs quick, reliable elapsed time calculations from simple clock‑in and clock‑out times.

FAQs

Can I use AM/PM instead of 24‑hour times?
This tool expects 24‑hour clock entries. Convert AM/PM times to 24‑hour format first (for example, 1 PM = 13:00, 12 AM = 0:00, 12 PM = 12:00).
Does this handle breaks automatically?
No. You’ll need to subtract any break time from the result yourself. For example, if the calculator shows 8 hours and you took a 30‑minute unpaid break, record 7.5 hours.

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This time duration calculator is for quick planning and estimation only and does not replace official time‑tracking or payroll systems. Always confirm recorded hours with your employer’s or client’s policies and tools, especially around overtime and daylight saving changes.