MCPCalc

Time Duration Calculator

Compute hours and minutes between two times.

Scratchpad (not saved)

What This Calculator Does

Calculate the exact time duration — hours and minutes — between any two times. This calculator handles same-day and overnight spans, including automatic next-day crossover when the end time is earlier than the start time.

It combines Start Hour, Start Minute, End Hour, End Minute to estimate Duration, Total Minutes.

Formula & Method

Duration calculation: Δt=tend−tstart\Delta t = t_{end} - t_{start} If the result is negative (overnight crossover), add 24 hours: Δt=Δt+24h\Delta t = \Delta t + 24h Hours and minutes are extracted from the total duration in minutes: hours=⌊Δtmin/60⌋hours = \lfloor \Delta t_{min} / 60 \rfloor, minutes=Δtminmod  60minutes = \Delta t_{min} \mod 60.

Notation used in the formulas: RR = Duration; x1x_{1} = Start Hour; x2x_{2} = Start Minute; x3x_{3} = End Hour; x4x_{4} = End Minute.

Method summary: inputs are normalized to consistent units, core equations are evaluated, then secondary values are derived and rounded for display.

Use this for shift duration calculations, time-tracking, travel planning, and any scenario where you need exact hours and minutes between two clock times on the same or consecutive days.

Worked Examples

Same-day example: 9:15 AM to 4:45 PM

Start: 9:15 AM (09:15) End: 4:45 PM (16:45) Duration = 16:45 − 09:15 = 7 hours 30 minutes

Overnight example: 10:30 PM to 7:15 AM

Start: 10:30 PM (22:30) End: 7:15 AM (07:15) 7:15 < 22:30, so this is an overnight span. Duration = (24:00 − 22:30) + 07:15 = 1:30 + 7:15 = 8 hours 45 minutes

How Overnight and AM/PM Crossovers Work

When the end time is earlier than the start time, the calculator automatically assumes the end time is on the next day. For example, a shift from 11:00 PM to 6:00 AM is treated as a 7-hour overnight shift rather than returning a negative result.

For AM/PM entry: make sure to select the correct AM or PM suffix. 12:00 PM is noon; 12:00 AM is midnight. The calculator handles 12-hour clock inputs by converting them to 24-hour format before computing.

How Many Hours Between Common Times

Here are pre-calculated durations for the most commonly searched time pairs:

Start TimeEnd TimeDuration
8:00 AM4:00 PM8 hours 0 minutes
8:00 AM4:30 PM8 hours 30 minutes
9:00 AM5:00 PM8 hours 0 minutes
9:00 AM5:30 PM8 hours 30 minutes
9:00 AM6:00 PM9 hours 0 minutes
6:00 AM6:00 PM12 hours 0 minutes
12:00 AM12:00 PM12 hours 0 minutes (midnight to noon)
10:00 PM6:00 AM8 hours 0 minutes (overnight)
11:00 PM7:00 AM8 hours 0 minutes (overnight)

Shift-Work Start and End Time Reference

Common shift combinations for 8-hour, 10-hour, and 12-hour schedules:

Shift LengthStart TimeEnd TimeNotes
8-hour7:00 AM3:00 PMDay shift (first shift)
8-hour3:00 PM11:00 PMAfternoon shift (second shift)
8-hour11:00 PM7:00 AMNight shift (third shift, overnight)
10-hour6:00 AM4:00 PMCommon in manufacturing
10-hour4:00 PM2:00 AMEvening 10-hour (overnight)
12-hour7:00 AM7:00 PMDay 12-hour (nursing, industrial)
12-hour7:00 PM7:00 AMNight 12-hour (overnight)

All overnight shifts crossing midnight are handled automatically — enter any start and end time and the calculator computes the correct duration.

Common Mistakes

  • Forgetting to set AM or PM correctly — entering 6:00 instead of 6:00 PM shifts the result by 12 hours.
  • Not accounting for overnight crossover — if your shift ends the next morning, the end time will appear earlier than the start time, which is handled automatically by this calculator.
  • Confusing time duration with a specific clock time — a duration of 8h 30m is not the same as 8:30 AM.

When Not To Use This Calculator

  • Multi-day spans longer than 24 hours — use the date difference calculator at /date/date-difference instead.
  • Time zone conversions — if your start and end times are in different time zones, use the time zone converter at /date/time-zone-converter first.

Frequently Asked Questions

How do you calculate time duration?
Subtract the start time from the end time. If both times are on the same day, the result is straightforward. If the end time is earlier than the start time (overnight), add 24 hours to the result to get the correct positive duration.
How many hours between two times?
Enter both times in this calculator and it will compute the exact hours and minutes between them. For example, 9:00 AM to 5:30 PM = 8 hours 30 minutes. 10:00 PM to 6:00 AM = 8 hours (overnight).
Can this handle overnight times (e.g. 11 PM to 6 AM)?
Yes. When the end time is earlier than the start time, the calculator automatically assumes the end time is the following day and computes the overnight duration correctly.
How do I calculate elapsed time?
Enter the start time and end time. The calculator returns elapsed hours and minutes. For spans longer than 24 hours, use the date difference calculator instead.

Inputs Used

  • Start Hour: Used directly in the calculation.
  • Start Minute: Used directly in the calculation.
  • End Hour: Used directly in the calculation.
  • End Minute: Used directly in the calculation.

See Also

Related Calculators