How to Convert Hours and Minutes to Decimal Hours for Payroll

Clocks use hours and minutes. Payroll and invoices use decimal hours. Somewhere between the two, a common mistake slips in: writing 7 hours 45 minutes as “7.45”. That’s 7 hours and 27 minutes in decimal terms, and the employee loses 18 minutes of pay.

The one rule: divide minutes by 60

An hour has 60 minutes, not 100. So:

Decimal hours = hours + minutes ÷ 60

• 30 minutes = 30 ÷ 60 = 0.5
• 45 minutes = 0.75
• 20 minutes = 0.333…, usually written 0.33
• 7 h 45 min = 7.75 hours

Going back the other way: multiply the decimal part by 60. 8.6 hours = 8 hours and 0.6 × 60 = 36 minutes.

Minutes to decimal chart

Working out a shift

Shift 08:45 to 17:15 with a 30-minute unpaid lunch:

1. End minus start:

   17:15 − 08:45 = 8 h 30 min

2. Minus the break:

   8 h 30 min − 30 min = 8 h 0 min

3. Decimal:

   8.00 hours

4. Pay at 1,200 an hour:

   8.00 × 1,200 = 9,600

It’s easiest to convert everything to minutes first: 08:45 is 525 minutes after midnight, 17:15 is 1,035. 1,035 − 525 − 30 = 480 minutes = 8 hours.

Overnight shifts

A night shift from 22:00 to 06:30 gives a negative answer if you simply subtract. Add 24 hours to the end time: 30:30 − 22:00 = 8 h 30 min = 8.5 hours. The time calculator does this automatically when the end is earlier than the start.

Adding up a week

Tip: add up the minutes first (2,315 minutes), then divide by 60 once. Rounding each day and then adding can drift by a few hundredths.

Rounding rules

Many payroll systems round clock times to the nearest 5, 6 (one tenth of an hour) or 15 minutes. In the USA, federal rules allow this as long as it averages out over time and doesn’t consistently underpay employees. With quarter-hour rounding, that leads to the so-called 7-minute rule: 1–7 minutes past a quarter rounds down, 8–14 rounds up. Some places are stricter (California courts, for example, have limited rounding), and many countries have their own rules, so check local law and your contract. When in doubt, paying for the exact minutes is always safe.

Overtime

Overtime is usually worked out on decimal hours too. If the threshold is 40 hours a week at 1.5× pay and someone works 43.5 hours, they get 40 hours at the normal rate plus 3.5 hours at 1.5×. The threshold and multiplier depend on your country and contract.

Doing it in Excel or Google Sheets

Spreadsheets store times as fractions of a day, so 6:00 is 0.25. To turn a time difference into decimal hours, multiply by 24:

• Start in A2, end in B2: =(B2-A2)*24
• Shift that may cross midnight: =MOD(B2-A2,1)*24
• Minus a 30-minute unpaid break: =MOD(B2-A2,1)*24-0.5
• Round to two decimals: wrap it in =ROUND(…,2)

Format the result cell as a number, not as a time, or the spreadsheet will show something like 8:00 again.

Common mistakes

• Writing minutes as decimals: 7:45 → 7.45 instead of 7.75.
• Forgetting unpaid breaks, or deducting paid ones.
• Negative overnight shifts from not adding 24 hours.
• Mixing formats on one timesheet: some days as h:mm, others as decimals.
• Spreadsheets showing time as a fraction of a day: in Excel or Google Sheets, multiply a time value by 24 to get decimal hours.

Frequently asked questions