Hours Calculator

About the Hours Calculator

How many hours are there between 8:45 am and 5:15 pm? How long was a night shift from 10 pm to 6:30 am? How many hours did a job, a journey or an event take from one day to another? The hours calculator answers these questions quickly, giving the time between two times in hours and minutes, decimal hours and total minutes.

It handles times in 24-hour format or with am and pm, works across midnight automatically, and can measure between two dates and times for spans longer than a day. You can also subtract a break, which is useful when working out paid hours.

How to Use the Hours Calculator

Choose Two times or Two dates and times.

Enter the start time and end time, such as 8:45 am and 5:15 pm or 08:45 and 17:15.

For the dates option, enter the start date and end date as well.

Optionally, enter a break in minutes to subtract.

How the Hours Are Calculated

  same day:      hours = end − start
  past midnight: hours = end + 24 h − start       (when end < start)
  across dates:  hours = (end date, end time) − (start date, start time)

  minus the break, then:
  decimal hours = minutes ÷ 60

Step-by-Step Example

From 8:45 am to 5:15 pm.

  8:45 → 16:45  = 8 hours
  16:45 → 17:15 = 30 minutes
  Total         = 8 h 30 min = 8.5 hours = 510 minutes

From 10 pm to 6:30 am with a 30-minute break.

  22:00 → 06:30 (next day) = 8 h 30 min
  Minus break              = 8 h

From 10 pm on 29 September to 6:30 am on 1 October 2026.

  22:00 Tue → 22:00 Wed = 24 h
  22:00 Wed → 06:30 Thu = 8 h 30 min
  Total                 = 32 h 30 min

12-Hour and 24-Hour Times

The calculator accepts both. In the 12-hour clock, 12 am is midnight and 12 pm is noon, which catches many people out: a shift from 12 pm to 8 pm is 8 hours, while one from 12 am to 8 am is also 8 hours but overnight. In the 24-hour clock there is no ambiguity — midnight is 00:00 and noon is 12:00 — which is why hospitals, transport and the military use it. If you type a time without am or pm, it is read as 24-hour time, so 5:15 means 05:15 in the morning.

Decimal Hours

Hours and minutes are not decimals. Eight and a half hours is written 8:30 on a clock but 8.5 as a decimal, because 30 minutes is half of 60. Timesheets, invoices and payroll systems usually need decimal hours so they can be multiplied by an hourly rate. The calculator gives both forms, so you can copy the one you need without converting by hand.

  15 min = 0.25 h     30 min = 0.5 h     45 min = 0.75 h
  10 min = 0.17 h     20 min = 0.33 h    40 min = 0.67 h

Common Uses

Work: hours in a shift, overtime, time spent on a client's project. Travel: the length of a drive, flight or train journey, including overnight trips. Study and sport: time spent revising or training. Home: how long a device was on, how long a slow cooker has been running, or how long a child slept. Business: opening hours, meeting lengths and response times.

Hours for Billing and Invoicing

Freelancers, consultants and tradespeople often bill by the hour, and many round time to a fixed increment: the nearest 6 minutes (a tenth of an hour), 15 minutes or 30 minutes. A job from 9:10 to 11:40 lasts 2 hours 30 minutes, or 2.5 hours, and at 60 an hour that is 150. Rounded up to the next quarter hour, a 2-hour-40-minute job would be billed as 2.75 hours. Whatever the rule, start from the exact time between start and finish — which this calculator gives — and then apply the rounding stated in your terms of business. Keeping exact records also makes it easy to answer a client who queries a bill.

Flights and Time Zones

When a journey crosses time zones, the clock times at each end are in different zones, so subtracting them directly gives the wrong answer. A flight leaving London at 10:00 and landing in New York at 13:00 local time takes 8 hours, not 3, because New York is 5 hours behind London. Convert both times to the same zone first, with a time zone converter, then use this calculator.

Daylight Saving

The two-dates option counts every day as 24 hours. On the night the clocks go forward in spring, a shift from 22:00 to 06:00 is really only 7 hours long; on the night they go back in autumn it is 9 hours. If a shift spans a clock change, add or subtract the hour yourself.

Understanding Your Result

The headline gives the hours and minutes.

The decimal hours line gives the same time as a decimal.

The minutes line gives the total in minutes.

The times line shows the times used and any break taken off.

The days line shows whole days when the span is longer than 24 hours.

When Should You Use This Calculator?

Use it to find hours worked on a shift, with or without breaks.

Use it to time journeys and events that cross midnight.

Use it to convert a span of time into decimal hours for a timesheet.

Use it to measure the hours between two dates and times.

Common Mistakes

Writing 8 hours 30 minutes as 8.3. In decimal hours it is 8.5.

Confusing 12 am and 12 pm. 12 am is midnight; 12 pm is noon.

Subtracting times in different time zones. Convert them first.

Forgetting the break. Subtract unpaid breaks for paid hours.

Typing a time without am or pm. 5:15 on its own means 05:15 in the morning.