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Time Calculator: Add Hours to a Date and Time

To add hours to a time, count forward on a 24-hour clock and carry every 24 hours into the next day: 72 hours after Mon, Jan 5, 2026, 9:00 AM is Thu, Jan 8, 2026, 9:00 AM. If the clocks change for daylight saving time in between, 72 real hours end an hour later or earlier on the clock, and the calculator shows both answers. It also finds the hours between two times and adds up a timesheet.

Updated Runs in your browser: nothing you enter is uploadedHow this tool works

Times are in your device's time zone, with daylight saving time taken into account.

Add or subtract hours

Add or subtract

Result

Thu, Jan 8, 2026, 9:00 AM

72 hours after Mon, Jan 5, 2026, 9:00 AM is Thu, Jan 8, 2026, 9:00 AM.

Amount of time
72 hours = 3 days
24-hour clock
2026-01-08 09:00
Counting clock hours
The same: no clock change in between

Hours between two dates and times

Result

80 hours, 30 minutes

From Mon, Jan 5, 2026, 9:00 AM to Thu, Jan 8, 2026, 5:30 PM is 80 hours, 30 minutes (3 days, 8 hours, 30 minutes).

Days, hours and minutes
3 days, 8 hours, 30 minutes
Decimal hours
80.5
Total minutes
4,830
On the clock
The same: no clock change in between

Add up hours (timesheet)

Write 7:45, 7.75, 7h 45m or a shift like 9:00-17:30 or 10pm-6am. Start a line with a minus to take time off, like -0:30 for a break.

Total

31:45 hours

5 entries add up to 31 hours, 45 minutes (31.75 hours).

Decimal hours
31.75
Total minutes
1,905
Days, hours and minutes
1 day, 7 hours, 45 minutes

Hours in days

HoursDays and hours
1212 hours
241 day
361 day, 12 hours
482 days
723 days
964 days
1004 days, 4 hours
1205 days
1687 days
33614 days
72030 days

Minutes as decimal hours

For timesheets and payroll: divide the minutes by 60.
MinutesDecimal hours
50.08
60.1
100.17
120.2
150.25
200.33
300.5
400.67
450.75
500.83

When the clocks change in 2026 and 2027

Most of the US and Canada change at 2:00 AM local time on the second Sunday in March and the first Sunday in November; the EU and UK at 1:00 AM UTC on the last Sundays of March and October. Arizona (outside the Navajo Nation) and Hawaii do not change.
RegionYearClocks go forward (1 hour)Clocks go back (1 hour)
US and Canada2026Sunday, March 8, 2026Sunday, November 1, 2026
US and Canada2027Sunday, March 14, 2027Sunday, November 7, 2027
EU and UK2026Sunday, March 29, 2026Sunday, October 25, 2026
EU and UK2027Sunday, March 28, 2027Sunday, October 31, 2027

How to add hours to a time

  1. Split the hours into days. Every 24 hours is one day: 72 hours is 3 days, 100 hours is 4 days and 4 hours.
  2. Add the leftover hours and minutes. Add them to the clock time on a 24-hour clock. If the total passes 24:00, subtract 24 and move one more day forward.
  3. Check for a clock change. If daylight saving time starts in between, the clock reads one hour later than you counted; if it ends, one hour earlier.
  4. Convert back to AM and PM if you need to. Hours 13 to 23 are 1 PM to 11 PM; 0:00 is 12 AM (midnight) and 12:00 is 12 PM (noon).

Frequently asked questions

What time will it be in 72 hours?
The same clock time three days from now, unless the clocks change for daylight saving time in between: then it is an hour later on the clock when the clocks go forward, or an hour earlier when they go back. Press Now and enter 72 hours to see the exact time where you are.
Is adding 24 hours the same as adding 1 day?
Almost always. On the night the clocks change they differ by an hour: 24 hours after noon on the Saturday before the US spring change is 1:00 PM on Sunday, while "1 day later" is noon, only 23 hours later. The calculator shows the exact elapsed time first and the same-clock-time answer beside it whenever they differ.
How many hours are between two times?
Enter both dates and times under "Hours between two dates and times". For times on the same day, subtract the start from the end on a 24-hour clock; for an overnight shift, add 24 hours to the end time first. 10:00 PM to 6:00 AM is 8 hours.
How do I add up hours and minutes for a timesheet?
Type one entry per line under "Add up hours": 7:45, 7.75, 7h 45m, or a shift such as 9:00-17:30. The total is shown as hours and minutes and as decimal hours, which is what most payroll systems want (7:45 is 7.75 hours).
Which time zone does the calculator use?
Your device's time zone, shown above the calculator, including its daylight saving rules. Every time you enter is read as a time on your own clock. A time that the clocks skip (such as 2:30 AM on the spring-forward night) is moved forward, and a time that happens twice is read as the first one; the result explains either case.
How do I convert minutes to decimal hours?
Divide the minutes by 60: 15 minutes is 0.25 hours, 30 minutes is 0.5 and 45 minutes is 0.75. The table above lists the common ones.

How it works

Times are read in your browser's own time zone with its daylight saving rules (JavaScript's Date), never sent anywhere. "Exactly N hours later" adds N × 60 minutes of real time to the start instant and reads the clock at the end. "Counting clock hours" moves the clock hands by the same amount while ignoring any clock change, which is what "the same time, three days later" means. They differ only when the UTC offset changes in between; the calculator finds each change to the minute and names it. A start time that does not exist (skipped by a spring-forward change) is moved forward by the gap, and one that happens twice is read as the first, as browsers do. The difference between two times is real elapsed minutes. Timesheet lines accept h:mm, decimal hours, "7h 45m" and start–end shifts (an end before the start runs past midnight).

Sources

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