Time in Decimal Calculator
Decimal time is a way of expressing hours and minutes as a single decimal number, where the fractional part represents a portion of an hour rather than whole minutes. For example, 1 hour and 30 minutes becomes 1.50 decimal hours, because 30 minutes is exactly half (0.50) of one hour. This format is the standard used in payroll processing, client billing, contractor invoicing, and project management time tracking because it allows direct multiplication by an hourly rate without an extra conversion step. The US Fair Labor Standards Act (FLSA) does not mandate a specific time format, but the decimal system is widely adopted by employers because modern payroll software requires decimal inputs. This calculator converts in both directions. In HH:MM to Decimal mode, enter the number of whole hours and the remaining minutes to get the decimal equivalent and the total number of minutes. In Decimal to HH:MM mode, enter a decimal hour value and the calculator breaks it back into whole hours, minutes, and the familiar HH:MM format. A quick-reference conversion table below covers the most common quarter-hour and half-hour increments.
Conversion formula
The conversion between HH:MM and decimal hours relies on the fact that one hour contains exactly 60 minutes.
HH:MM to decimal:
decimalHours = hours + (minutes / 60)
totalMinutes = (hours * 60) + minutes
Decimal to HH:MM:
hours = Math.floor(decimalHours)
minutes = Math.round((decimalHours - hours) * 60)
Example: 2 hours 45 minutes
decimal = 2 + (45 / 60) = 2 + 0.75 = 2.75
totalMins = (2 * 60) + 45 = 165
Quick-reference conversion table
Common time values in HH:MM and decimal hours:
| HH:MM | Decimal hours | Total minutes |
|---|---|---|
| 0:15 | 0.25 | 15 |
| 0:30 | 0.50 | 30 |
| 0:45 | 0.75 | 45 |
| 1:00 | 1.00 | 60 |
| 1:15 | 1.25 | 75 |
| 1:30 | 1.50 | 90 |
| 1:45 | 1.75 | 105 |
| 2:00 | 2.00 | 120 |
| 2:30 | 2.50 | 150 |
| 3:00 | 3.00 | 180 |
| 4:00 | 4.00 | 240 |
| 6:00 | 6.00 | 360 |
| 7:30 | 7.50 | 450 |
| 8:00 | 8.00 | 480 |
Time in decimal calculator: frequently asked questions
What is decimal time?
Decimal time expresses a duration as a decimal fraction of an hour rather than in hours and minutes. For example, 1 hour and 30 minutes equals 1.5 decimal hours. This format is widely used in payroll, billing, and time-tracking systems because multiplying decimal hours by an hourly rate gives the correct pay amount directly.
How do I convert minutes to decimal hours?
Divide the number of minutes by 60. For example, 45 minutes divided by 60 equals 0.75 decimal hours. For a combined time of 2 hours and 45 minutes, take 2 plus (45 divided by 60), which equals 2.75 decimal hours.
How do I convert decimal hours to minutes?
Multiply the decimal fraction part by 60. For example, 0.75 decimal hours multiplied by 60 equals 45 minutes. For 2.75 hours, the whole number is 2 hours and 0.75 multiplied by 60 equals 45 minutes, giving 2 hours and 45 minutes.
Why is decimal time used in payroll?
Multiplying decimal hours directly by an hourly rate gives the correct pay amount without any extra conversion steps. For example, 1.5 hours at $20.00 per hour equals $30.00. Using the HH:MM format of 1:30 requires converting to decimal first before multiplication, which adds a step and increases the chance of error.
What is 1 hour 45 minutes in decimal?
1 hour 45 minutes equals 1.75 decimal hours. The calculation is: 45 divided by 60 equals 0.75, then add 1 whole hour to get 1.75. You can verify this: 0.75 multiplied by 60 equals 45 minutes.
Official sources
- US Department of Labor Fair Labor Standards Act timekeeping requirements: dol.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.