Hours Calculator

How to use the Hours Calculator

1. To time a shift, enter the start and end times and any unpaid break. Overnight shifts are handled automatically.
2. To total several durations, type each one as h:mm (or 1.5, or 1h 30m), and set rows to Subtract where needed.
3. Use + Add time for more rows; the total updates as you type.
4. Convert any hh:mm value to decimal hours, or the other way round, in the bottom box.

Features

• Hours and minutes between two times, crossing midnight
• Unpaid break deduction for shift and timesheet work
• Add and subtract any number of durations
• Accepts 1:30, 1.5, 1h 30m and 90m formats
• Two-way hh:mm and decimal hours converter
• Totals over 24 hours shown in days as well

Hours between two times

To find the time between a start and an end time, the calculator converts both to minutes after midnight, subtracts, and converts back to hours and minutes:

duration = end − start, and if the end is earlier than the start, the period crossed midnight, so duration = end − start + 24 hours.

For example, a night shift from 22:30 to 06:15 gives 06:15 − 22:30 = −16 h 15 min, plus 24 h = 7 h 45 min. Any unpaid break is then subtracted, so 09:00 to 17:30 with a 30-minute lunch is 8 hours. This part handles periods up to 24 hours; for longer spans use Days Between Dates.

Adding and subtracting hh:mm durations

Times do not add like decimals, because an hour has 60 minutes, not 100. Adding 1:45 and 2:30 digit by digit gives 3:75, which is really 4:15. The calculator adds everything in minutes and then splits the total back into hours and minutes. Each row accepts:

• 1:30 for hours and minutes, or 1:30:15 with seconds
• 1.5 for decimal hours
• 1h 30m, 90m or 2h

Set a row to Subtract to take time away, such as breaks or time already used. The starting example, 1:45 + 2:30 − 0:50, totals 3:25.

Converting to decimal hours

Payroll systems and invoices usually want hours as a decimal number. Divide the minutes by 60 and add them to the hours:

decimal hours = hours + minutes ÷ 60

So 7:45 is 7 + 45 ÷ 60 = 7.75 hours, and 8 h 20 min is about 8.333 hours. To go the other way, multiply the decimal part by 60: 6.4 hours is 6 hours and 0.4 × 60 = 24 minutes.

Common mistakes

• Reading 7.30 as seven and a half hours. On a timesheet, 7.30 might mean 7 h 30 min (7.5 decimal hours) or 7.3 decimal hours (7 h 18 min). Use a colon for clock-style times to avoid confusion.
• Forgetting overnight shifts. If the end time is earlier than the start, the shift ran past midnight and 24 hours must be added.
• Rounding too early. Convert the weekly total to decimal at the end instead of rounding each day, or small errors add up.

For a complete weekly timesheet with pay, try the Timesheet Calculator.

Frequently asked questions