Elapsed Time Calculator

Time & Date

Quickly find the time difference between two dates and times. Supports 24‑hour and AM/PM formats, crossing midnight, and multiple intervals (timesheets).

Time format

Options

How to use the elapsed time calculator

  1. Choose the time format (24‑hour or 12‑hour AM/PM).
  2. Enter the start date and time for your interval.
  3. Enter the end date and time. If the end time is earlier than the start time on the same date, the tool assumes the end is on the next day.
  4. Click “Calculate elapsed time” to see the duration in days, hours, minutes, and seconds.
  5. Use “Add interval” to add more rows (for example, multiple work shifts). The calculator will show each interval and the grand total.

What is elapsed time?

Elapsed time is the amount of time that passes between a start moment and an end moment. It is often used for:

  • Tracking work hours or billable time
  • Measuring travel time or event duration
  • Calculating time between dates (e.g., project milestones)
  • School math problems involving clocks and calendars

Elapsed time formula

Conceptually, elapsed time is:

elapsed time = end date‑time − start date‑time

In practice, computers convert both date‑times to a single unit (such as milliseconds since a reference point), subtract, then convert back:

Δt = tend − tstart
days = ⌊Δt / 86 400 s⌋
hours = remaining seconds ÷ 3 600
minutes = remaining seconds ÷ 60
seconds = remaining seconds

Examples

Example 1 – Same day

Start: 09:15
End: 14:45

From 09:15 to 14:15 is 5 hours, plus 30 minutes more to 14:45:

Elapsed time = 5 hours 30 minutes

Example 2 – Crossing midnight

Start: 22:30 on March 10
End: 01:15 on March 11

From 22:30 to midnight is 1 hour 30 minutes, plus 1 hour 15 minutes to 01:15:

Elapsed time = 2 hours 45 minutes

Common questions

Does the calculator handle multiple days?

Yes. Because you can set different start and end dates, the tool works for durations of minutes, hours, days, or even months and years. The result is always shown as a combination of days, hours, minutes, and seconds, plus total hours and total minutes.

Can I use it as a timesheet hours calculator?

Yes. Add one interval per shift (for example, morning and afternoon), then read the Total elapsed time at the top. You can also see the total in decimal hours, which is convenient for payroll and billing.

Elapsed Time Calculator – FAQ

How do you calculate elapsed time between two dates and times?

Convert both date‑times to a single scale (for example, seconds since a reference date), subtract the start from the end, then convert the difference back into days, hours, minutes, and seconds. The calculator automates this and also handles leap years and different month lengths using your browser’s date engine.

Can this elapsed time calculator handle times that cross midnight?

Yes. If the end date is the same as the start date but the end time is earlier, the calculator assumes the end is on the next day. You can also explicitly set the end date to the following day or any later date for longer spans.

What time formats are supported?

You can choose between 24‑hour time (00:00–23:59) and 12‑hour AM/PM time. The inputs and labels adapt automatically when you switch formats, and the underlying calculation is always done in 24‑hour time for accuracy.

Can I add multiple time intervals together?

Yes. Use the “Add interval” button to create more rows. Each row has its own start and end date‑time. The calculator shows the elapsed time for each interval and the grand total across all rows, which is ideal for timesheets, project logs, or multi‑day events.