Time Duration Calculator for Hours Between Times, Overnight Shifts, and HH:MM:SS
Calculate how much time passes between a start date-time and an end date-time. Use it to find hours and minutes between times, elapsed time across midnight, work shift duration, decimal hours, HH:MM:SS, date-time differences, and total seconds when you already know both endpoints.
Endpoint duration mode
Use this page when you already know both the start and the end. If you know one time plus an offset, use Add/Subtract Time instead. Open Add/Subtract Time
Try a common duration
Local time calculation
The browser uses your local time zone for the selected date and time values.
Result
8 hr 30 min
7/3/2026, 9:00:00 AM to 7/3/2026, 5:30:00 PM
08:30:00 HH:MM:SS
Range check
Same-day range
Start and end share the same local date.
total hours
8.5
total minutes
510
total seconds
30,600
total days
0.3542
A time duration between two times is the end date-time minus the start date-time.
The result shows a readable duration plus total hours, minutes, seconds, and days. For overnight ranges, make the end date the next day.
Use complete start and end values
This page compares two endpoints. A date plus a time removes ambiguity for overnight and multi-day ranges.
Keep time zones separate
This calculator uses the local time from your browser. Convert time zones first if the endpoints are in different regions.
duration = end date-time - start date-time
Total hours, minutes, seconds, days, and the HH:MM:SS label are derived from the same millisecond difference.
Use this page for questions like how many hours are between 9 AM and 5:30 PM, how many minutes elapsed between two log entries, or how long a date-time range lasts.
Use the add/subtract page when you have one known date-time and need to move it forward or backward by hours, days, weeks, or months.
Calculations are handled in the browser for this tool based on the current public implementation.
Same-day work shift
09:15 to 17:45 on the same date is 8 hours 30 minutes, or 8.5 total hours.
Overnight range
22:00 today to 06:00 tomorrow is 8 hours. Set the end date to the next day.
Local-time limits
The selected dates and times use the local time zone from your browser and do not apply payroll rounding, breaks, holidays, or cross-time-zone conversion.
Forgetting overnight dates
A shift from 10 PM to 6 AM needs the end date set to the next day. Same-date inputs produce a negative or wrong range.
Mixing time zones
This page uses local browser time. Convert endpoints first when the start and end happen in different regions.
Using duration math for payroll rules
Break deductions, overtime, rounding, holidays, and policy rules are not applied. Use this for raw elapsed time only.
Work shifts
Calculate hours between a start and end shift time.
Overnight ranges
Set the end date to tomorrow when the range crosses midnight.
Event schedules
Find total duration for sessions, launches, classes, or appointments.
Log cleanup
Convert timestamp ranges into total minutes, seconds, or human-readable elapsed time.
Hours between two times
Calculate total hours and minutes from one local endpoint to another.
Overnight time duration
Set the end date to the next day for shifts or events that cross midnight.
Decimal hours calculator
Convert the same range into decimal hours for timesheets or planning notes.
Date time difference calculator
Compare full date-time values across same-day, overnight, or multi-day ranges.
How do I calculate time between two times?
Enter the start date-time and end date-time. The calculator subtracts the start from the end and returns the elapsed time in days, hours, minutes, and seconds.
How many hours are between two times?
Enter both endpoints and read the total hours card. The page also shows total minutes, total seconds, total days, and a readable duration.
Can this calculate time across midnight?
Yes. Set the end date to the next day for an overnight range, such as 22:00 today to 06:00 tomorrow.
Can I calculate the duration between two dates?
Yes. Use the date fields with the start and end times you want to compare. The result includes total days plus smaller time units.
What is elapsed time?
Elapsed time is the amount of time that passes between a start point and an end point. It is different from adding an offset to one known time.
What is the difference between time duration and adding time?
This duration calculator compares two endpoints. The add/subtract time calculator starts with one date-time and moves forward or backward by an offset.
Suggested workflow
Time range planning path
Calculate a start-to-end duration, then refine the same plan with business-day, unit, or time-zone tools.