Hours calculator: time between two times

How the duration is calculated

Each time is turned into minutes since midnight, then the start is subtracted from the end. If the end is earlier than or equal to the start, 24 hours are added: that is the midnight crossing.

\[ \text{duration} = (\text{end} - \text{start} ,\ + 24 \, \text{h} \ \text{if negative}) - \text{break} \]

Example: 10:00 PM to 6:00 AM gives 6:00 − 22:00 = −16 hours, which becomes 8 hours after adding 24.

Converting to decimal hours

Payroll and spreadsheets use decimal hours. Divide the minutes by 60.

\[ \text{decimal hours} = \text{hours} + \dfrac{\text{minutes}}{60} \]

Do not read 7:50 as 7.5 hours. Minutes run to 59, not 99.

Adding or subtracting hours from a time

The second mode returns the finishing time and says "next day" when it passes midnight. It works for travel time, cooking, a flight or the end of a shift.

Hours calculator: worked examples step by step

For any hours calculator job, use the same method. First, enter the start time. Then enter the end time. Next, subtract any break. Finally, read the result in hours and minutes and in decimal hours.

For example, you start at 9:15 AM and finish at 5:45 PM, with a 45 minute break. The gross time is 8 hours 30 minutes. After the break, 7 hours 45 minutes remain, or 7.75 hours. So you can enter 7.75 on an hourly invoice. Likewise, a shift from 10 PM to 6 AM lasts 8 hours, because the hours calculator crosses midnight on its own.

Hours calculator: minutes and decimal hours

Many people slip when they convert minutes. In fact, 7:30 does not equal 7.30 but 7.5. You must divide the minutes by 60. Here are the most useful conversions.

If you bill in quarter hour blocks, round to a multiple of 0.25. However, never round a work time against yourself without a written agreement.

Hours calculator: where it helps

This math helps every day. For example, a freelancer tracks the time on a project to write an invoice. Then an employee checks a timesheet before payday. Also, a parent counts a drive or a game to plan the afternoon.

To add up several days, switch to the time card calculator. If you need days instead of hours, use the days between dates calculator. Finally, to time something live, open the online stopwatch.

Hours calculator: frequent mistakes

Three mistakes come up often. First, people forget that a night shift crosses midnight. If the end is before the start, add 24 hours. Second, they read 1.30 hours as 1:30, but 1.30 hours is 1:18. Third, they forget the break, which inflates the total.

For example, from 1:40 PM to 5:10 PM the duration is 3 hours 30 minutes. However, if you write 3.30 on an invoice, you lose 12 minutes. So always check the conversion before you send a document.