Everyday Math5 min read•Updated 2026-09-07
How to Calculate Work Hours & Time Duration: Timesheets & Decimal Hours
Compute exact elapsed shift times, deduct unpaid lunch breaks, and convert minutes to decimal hours for payroll.
MX
MultiToolX Technical Team
Payroll & Operations
Key Takeaways
- Decimal Hours Formula: Decimal Hours = Hours + (Minutes / 60).
- Common Conversions: 15 mins = 0.25 hrs, 30 mins = 0.50 hrs, 45 mins = 0.75 hrs.
- Overnight shifts crossing midnight require adding 24 hours (1,440 minutes) to the end time.
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1. Converting Minutes to Decimal Hours
Corporate payroll systems and ERP software (ADP, Paychex, QuickBooks) require hours entered as decimal fractions, not hours and minutes:
Decimal Hours = Hours + (Minutes / 60)
Common Timesheet Conversions:
- 7 hours 15 minutes = 7 + (15/60) = 7.25 hours
- 8 hours 30 minutes = 8 + (30/60) = 8.50 hours
- 7 hours 45 minutes = 7 + (45/60) = 7.75 hours
- 8 hours 20 minutes = 8 + (20/60) = 8.33 hours.
2. Deducting Breaks and Calculating Pay
Under labor regulations, meal breaks over 30 minutes are generally unpaid:
Net Work Hours = (End Time - Start Time) - Unpaid Break Duration
Gross Earnings = Net Decimal Hours * Hourly Wage
Example:
Shift from 08:30 AM to 05:15 PM with a 45-minute unpaid lunch break:
- Total Elapsed = 8 hours 45 minutes = 525 minutes
- Minus Break = 525 - 45 = 480 minutes = 8.00 decimal hours
- At $30/hr: 8.00 * $30 = $240.00 gross pay.
Frequently Asked Questions
How do you calculate shifts that span across midnight?
Convert both times into minutes from midnight. If the end time is numerically smaller than the start time, add 1,440 minutes (24 hours) to the end time before subtracting.
What is the 7-minute rounding rule in payroll?
The FLSA allows employers to round employee punch times to the nearest quarter-hour (15 minutes). Punches between 1 and 7 minutes round down; punches between 8 and 14 minutes round up.
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