Hours to Decimal Calculator

Payroll systems and invoices want decimal hours. Clocks, rosters and people want hours and minutes. This converts between the two, which sounds trivial until you are doing it for a fortnight of timesheets and realise that 7 hours 30 minutes is 7.5 but 7 hours 20 minutes is 7.33 recurring, and that rounding it to 7.3 quietly underpays someone by two minutes every single day. That is the reason this conversion matters more than it looks: minutes are base sixty and decimals are base ten, so only the quarter hours land on tidy numbers. A third of an hour is 0.333 and a sixth is 0.166, and neither terminates. Enter hours and minutes and you get the decimal figure, the total in minutes, and, if you add an hourly rate, what those hours are worth. The calculator carries the decimal to four places so you can see exactly where a rounding decision is being made rather than having it made for you. In New Zealand this matters for keeping accurate records of hours worked, which employers are required to do, and for anyone invoicing by the hour who wants their total to reconcile against their timesheet rather than being a few dollars adrift each month.

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$
7.3333
decimal hours
Rounded to 2 places7.33
Total minutes440
Back as hours and minutes7:20
Pay at this rate$183.33
Cost of rounding to 2 places$0.08

Only the quarter hours convert to tidy decimals. A third of an hour is 0.3333 recurring, so any rounding is a real decision about who absorbs the difference.

How it works

Decimal hours are the hours plus the minutes divided by 60. So 7 hours 20 minutes is 7 plus 20/60, which is 7.3333 recurring. Going the other way, the whole number is the hours and the decimal part multiplied by 60 gives the minutes. Total minutes is the hours multiplied by 60 plus the minutes. Pay is the decimal hours multiplied by the hourly rate, calculated on the unrounded figure. The rounding line shows the difference between paying on the exact decimal and paying on the two-place rounded one, which is what a payroll system will usually do.

Worked example

Take 7 hours and 20 minutes, the default. Twenty minutes is 20 divided by 60, which is 0.3333 recurring, so the decimal figure is 7.3333. Rounded to two places for payroll that becomes 7.33. At $25 an hour, the exact figure pays 7.3333 x 25, which is $183.33, while the rounded figure pays 7.33 x 25, which is $183.25. The difference is 8 cents on one shift. Across a fortnight of ten shifts that is 80 cents, and across a year of the same shift it is close to $21.

Related calculators

Data sources: Employers in New Zealand must keep accurate records of hours worked under the Employment Relations Act 2000. See Employment New Zealand for record-keeping requirements.

Frequently asked questions

How do I convert minutes to decimal hours?

Divide the minutes by 60. Fifteen minutes is 0.25, thirty is 0.5 and forty-five is 0.75. Minutes that are not a quarter hour do not give a tidy decimal: twenty minutes is 0.3333 recurring and ten minutes is 0.1667.

What is 7 hours 30 minutes in decimal?

7.5 hours. Thirty minutes is half an hour, which is 0.5 in decimal, so 7 hours 30 minutes is 7.5. This is one of the few conversions that lands on a tidy number, because 30 divides evenly into 60.

Does rounding decimal hours matter?

It can. Rounding 7.3333 to 7.33 loses a fraction of a minute each time, and repeated across every shift for a year it adds up to a real amount. Employers in New Zealand are required to keep accurate records of hours worked, so it is worth knowing which direction your payroll system rounds.

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