Time calculator: hours and minutes

Decimal hours: why 8:30 is 8.5, not 8.3

Payroll and invoices usually want hours as a decimal number, while clocks count minutes in sixties. To turn minutes into a decimal, divide them by 60: 30 minutes is 0.5 hours, so 8 hours 30 minutes is 8.5 hours. Writing it as 8.30 would pay 18 minutes short.

Going the other way, multiply the decimal part by 60: 7.75 hours is 7 hours and 45 minutes. Octoolo shows both at once and rounds decimal hours to two places; the minutes line is exact. Multiply decimal hours by a rate in the calculator, or let the timesheet do it.

Shifts with breaks, and shifts past midnight

In Between two times, an end earlier than the start counts as the next day. A night shift from 22:00 to 06:30 is 8 hours 30 minutes; with a 30-minute Break it reads 8:00 worked, or 8.00 decimal hours. A day from 09:00 to 17:30 with the same break is also 8:00.

The line under the answer spells out what was counted, such as “8 h 30 min from 22:00 to 06:30 the next day, less a 30 min break”, so you can check it against the rota. If the break is longer than the time between the two, the tool says so instead of showing a negative day. The times use your Windows clock format, so they may show as 10:00 PM rather than 22:00.

Adding and taking away hours

Add and subtract keeps a list of lengths of time, each one added or taken away. It reads them the way people write them:

• 1:30 or 1:30:00: hours, minutes and seconds with colons
• 1h 30m, 90m, 2 hours 5 minutes, 2d 4h: with units
• 1.5h or just 1.5: a number on its own is hours

The example adds 2:45 and 1:30 and takes away 0:15, which makes 4:00. A total over 24 hours is also given in days, so 26:30 reads as 1 day and 2:30. Switch on Start from a clock time to find when something ends: 09:00 plus 7:45 is 16:45, and the answer says when it runs into the next day. A line that cannot be read turns red and the note says which line it is.

A week's timesheet

Timesheet has a row for each day from Monday to Sunday, with a start, an end and a break. It starts with Monday to Friday from 09:00 to 17:30 with 30-minute breaks, a 40:00 week, so you only change what was different. Each day shows its hours; the week shows its total in hours:minutes and decimal hours, and Pay appears when you fill in Pay per hour.

The week is kept on your computer, so it is still there the next time you open the Calculator; Clear empties it. Copy table copies the days with their decimal hours as columns that paste straight into a spreadsheet, for example a spreadsheet where you track a month. It does not work out overtime or tax: those rules differ between countries and contracts.