How to convert time to decimal hours
To turn hours and minutes into decimal hours, divide the minutes by 60 and add them to the hours. For example, 02:30 = 2 + (30 ÷ 60) = 2.5 hours. 15 minutes is 0.25 hours, and 45 minutes is 0.75 hours.
The quarter-hour values are worth memorising because rotas are usually built on them: 0:15 is 0.25, 0:30 is 0.5, 0:45 is 0.75 and 1:00 is 1.0. Everything else follows the same division - 0:20 is 0.333, 0:40 is 0.667 and 0:10 is 0.167.
A quick pass through the decimal hours to time calculator saves a step later on.
How to use this calculator
Enter a time in HH:MM and the decimal value appears instantly. This is the format most payroll systems expect. To convert seconds to hours instead, use the seconds to hours calculator, or split hours with the hours to minutes calculator.
Worked example for a week: shifts of 8:15, 7:30, 9:45, 6:20 and 8:00 convert to 8.25, 7.5, 9.75, 6.333 and 8.0, totalling 39.833 hours. At 18 dollars an hour that is 717.00, whereas adding the HH:MM figures as if they were decimals would have given 38.10 hours and short-changed the week by nearly two hours of pay.
Why decimal hours matter
Payroll, billing and timesheet software usually multiply an hourly rate by decimal hours, not by HH:MM. Converting 7:45 to 7.75 hours before multiplying avoids errors that come from treating minutes as if they were base-100.
Round only once, at the end. Rounding every shift to two decimals before summing introduces small errors that compound across a month, and many payroll systems instead round the total to the nearest hundredth or to the nearest six-minute (0.1 hour) unit. Check which rule your employer or client uses before invoicing.
Frequently asked questions
- What is 2:30 in decimal hours?
- 2:30 is 2.5 decimal hours, because 30 minutes ÷ 60 = 0.5 added to 2 hours.
- How do I convert time to a decimal?
- Divide the minutes by 60 and add the result to the number of hours.
- What is 15 minutes as a decimal?
- 15 minutes is 0.25 hours, since 15 ÷ 60 = 0.25.
- Why do payroll systems use decimal hours?
- Pay is calculated as rate × decimal hours. Converting first prevents mistakes from treating minutes as hundredths.
- How do I include seconds in the conversion?
- Divide the seconds by 3,600 and add them on. So 7:45:30 is 7 + 45/60 + 30/3600 = 7.7583 hours. Most timesheets round to two decimals, which would make that 7.76 hours.