Time Duration Calculator — Hours Between Dates, Time Zones

How to calculate a time duration

Enter the start date and time. Now fills in the current time on your device.
Enter the end date and time. For a night shift, use +1 day so the end is the next morning.
Pick the time zone. It starts on your device’s zone. For a trip or a call between cities, switch on The end is in another time zone and pick the second zone.
Read the answer in days, hours and minutes, as hours:minutes (8:30) for a timesheet, as decimal hours (8.5) for pay, and in minutes.

The answer is the real time that passes between the two moments. When a daylight saving change or a time-zone change sits in between, the card also shows what the clocks say, and why the two differ.

Daylight saving time: the 23- and 25-hour days

In most of the U.S., clocks go forward one hour at 2:00 AM on the second Sunday of March and back one hour at 2:00 AM on the first Sunday of November (15 U.S.C. 260a). That makes one 23-hour day and one 25-hour day each year:

Night	What the clocks do	11 PM Saturday → 7 AM Sunday	1:00 AM → 3:00 AM
Second Sunday of March	2:00 AM jumps to 3:00 AM	7 hours (clock difference 8)	1 hour
First Sunday of November	2:00 AM goes back to 1:00 AM, so 1:00–1:59 happens twice	9 hours (clock difference 8)	4 hours

The real number is the one that matters for hours worked: under federal wage rules, non-exempt employees are paid for the hours actually worked, so a fall-back night shift is 9 hours (HR Daily Advisor). A time that falls in the skipped hour, such as 2:30 AM on a March changeover night, does not exist; the calculator reads it as 3:30 AM and says so. A time in the repeated hour, such as 1:30 AM in November, is taken as the first 1:30 (daylight time).

Hawaii and most of Arizona do not observe daylight saving time, nor do Puerto Rico, Guam and the U.S. Virgin Islands (NIST). Pick Arizona (Phoenix) or Hawaii and the changeover nights are ordinary 24-hour days.

U.S. daylight saving dates

Year	Clocks forward (2:00 → 3:00 AM)	Clocks back (2:00 → 1:00 AM)
2026	Sunday, March 8	Sunday, November 1
2027	Sunday, March 14	Sunday, November 7
2028	Sunday, March 12	Sunday, November 5

Time zones and flights

Airline tickets give departure and arrival in local time at each airport. Enter each one in its own zone and the calculator subtracts the real moments:

Trip	Departs (local)	Arrives (local)	Duration	Clock difference
New York → Los Angeles	9:00 AM ET	12:30 PM PT	6 h 30 min	3:30
Los Angeles → New York, overnight	10:30 PM PT	6:45 AM ET next day	5 h 15 min	8:15
Chicago → Denver	8:00 AM CT	9:40 AM MT	2 h 40 min	1:40
New York → London	7:00 PM ET	7:05 AM UK next day	7 h 5 min	12:05

Times are for October 2026, when New York is on daylight time (UTC−4). The card under the answer shows each moment’s UTC offset, so you can check which offset was used. Arizona is on the same clock as Los Angeles in summer and as Denver in winter.

Hours and minutes to decimal hours

Timesheets and payroll often want decimal hours: divide the minutes by 60.

Minutes	Decimal	Minutes	Decimal
5	0.08	35	0.58
10	0.17	40	0.67
15	0.25	45	0.75
20	0.33	50	0.83
25	0.42	55	0.92
30	0.5	60	1

So 7 hours 45 minutes is 7.75 hours; at $18 an hour that is 7.75 × 18 = $139.50. For a share of a shift or a rate change, the percentage calculator shows each step.

Time differences in Excel and Google Sheets

Excel stores a time as a fraction of a day, so the formulas need a little care:

Want	Formula (start in A1, end in B1)	9:15 AM → 5:45 PM
Duration as h:mm	`=B1-A1`, formatted `[h]:mm`	8:30
Decimal hours	`=(B1-A1)*24`	8.5
Across midnight (times only)	`=MOD(B1-A1,1)*24`	— (10 PM → 6:30 AM = 8.5)
Minutes	`=(B1-A1)*1440`	510

If a night-shift row shows ####, the end time is earlier than the start time and Excel cannot show negative time: use the MOD formula or enter the date with each time. Spreadsheets ignore daylight saving changes and time zones, so check changeover nights and trips here.

To count whole days between two dates — with business days and holidays — use the days between dates calculator. To find the date a number of days or business days away, use the date calculator. To add up or subtract hours and minutes, or plan a schedule from a start time, use the time calculator. An hours calculator for timesheets with breaks and several shifts is on the way.

Frequently asked questions

How many hours is 9 AM to 5:30 PM?

8 hours 30 minutes, which is 8.5 hours or 510 minutes. Take a lunch break off separately: with a 30-minute break it is 8 hours.

How do I calculate hours across midnight?

Give the end its own date. 10:00 PM on October 7 to 6:30 AM on October 8 is 8 hours 30 minutes. The +1 day button moves the end date forward for night shifts.

How long is a night shift when the clocks change?

On the night daylight saving time ends, the hour from 1:00 to 2:00 AM happens twice, so 11 PM Saturday to 7 AM Sunday is 9 hours, not 8. On the night it starts, 2:00 AM jumps to 3:00 AM and the same shift is 7 hours. Pay rules count the hours actually worked; this calculator shows the real time and the clock difference side by side.

How do I find a flight's duration across time zones?

Switch on 'The end is in another time zone', enter the departure time in the departure city's zone and the arrival time in the arrival city's zone — the local times on your ticket. A 9:00 AM departure from New York landing at 12:30 PM in Los Angeles is 6 hours 30 minutes in the air.

How do I convert minutes to decimal hours?

Divide the minutes by 60: 30 minutes is 0.5 hours, 15 is 0.25, 45 is 0.75 and 20 is 0.33. So 8 hours 30 minutes is 8.5 hours, not 8.30. The answer above shows both the h:mm and the decimal form.

Why do other calculators give a different answer around daylight saving time?

Most subtract the clock readings, so 1:00 AM to 3:00 AM on the second Sunday of March comes out as 2 hours, though only 1 hour passes. This calculator works out the real moments in your time zone, so it gives 1 hour and says the clocks moved forward at 2:00 AM.