Decimal Hours vs. Minutes: Why Payroll Uses Decimal Time
Payroll systems use decimal hours (like 7.5 instead of 7 hours 30 minutes) because it's directly multipliable by an hourly rate without a separate minutes-to-fraction conversion step — decimal format simplifies the arithmetic for both payroll software and manual calculation alike.
Seeing "7.5 hours" on a paycheck instead of "7 hours 30 minutes" isn't payroll being imprecise — it's a deliberate format choice that makes the actual pay calculation simpler and less error-prone.
Why decimal format simplifies the math
Multiplying an hourly rate directly by hours and minutes doesn't work cleanly, since minutes aren't a base-10 fraction of an hour — 30 minutes isn't "0.30" of an hour, it's 0.5. Converting to decimal hours upfront (7 hours 30 minutes becomes 7.5) means the rest of the calculation is a single, simple multiplication: hours × rate.
Common conversions worth knowing
15 minutes = 0.25 hours, 30 minutes = 0.5 hours, 45 minutes = 0.75 hours — these three cover most everyday timesheet entries. For any other number of minutes, dividing by 60 gives the exact decimal equivalent (20 minutes ÷ 60 = 0.33 hours, for example).
Where mixing the formats causes errors
Manually treating 30 minutes as "0.30" instead of "0.5" — a natural but incorrect assumption based on how the numbers look — is one of the most common timesheet calculation mistakes, and it understates pay for that time by a meaningful margin. Converting minutes correctly before doing any further math avoids this entirely.