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Net Hours Worked
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Sources & Methodology
Time difference calculations use standard clock arithmetic verified against U.S. Department of Labor timekeeping requirements and FLSA overtime guidelines.
U.S. Department of Labor — Fair Labor Standards Act (FLSA)
Federal law governing hours worked, overtime thresholds, and timekeeping requirements used to verify net hours and break deduction logic.
U.S. Bureau of Labor Statistics — American Time Use Survey
Reference for standard shift structures, average work hours, and break time conventions used in the preset examples and educational content.
NIST — Time and Frequency Division: Civil Time
National Institute of Standards and Technology reference for the definition and arithmetic of civil time used in clock-based calculations.
Methodology: Both times are converted to total minutes since midnight (hours × 60 + minutes). The difference is computed. If the result is negative (end time before start time), 1440 minutes (24 hours) are added to handle overnight/cross-midnight shifts. Break minutes are then subtracted. The final minutes are converted to hours + minutes (clock format) and decimal hours (minutes ÷ 60). Decimal hours are rounded to 2 decimal places for payroll use.
⏱ Last reviewed: April 2026
How to Calculate Hours Between Two Times
Calculating the hours between two times is one of the most common everyday math tasks — whether you are filling in a timesheet, calculating shift pay, tracking billable hours, or figuring out how long a task took. The core method is straightforward: convert both times to minutes, subtract, and convert back. The complication arises when shifts cross midnight, which requires a simple adjustment.
The Time Difference Formula
Total Minutes = (End Hour × 60 + End Minutes) − (Start Hour × 60 + Start Minutes)
If result is negative: add 1440 (handles overnight shifts)
Net Minutes = Total Minutes − Break Minutes
Decimal Hours = Net Minutes ÷ 60
Example: 9:00 AM to 5:30 PM with 30-minute lunch
End = 17 × 60 + 30 = 1050 min | Start = 9 × 60 + 0 = 540 min
Gross = 1050 − 540 = 510 minutes (8h 30m)
Net = 510 − 30 = 480 minutes = 8 hours = 8.00 decimal
End = 17 × 60 + 30 = 1050 min | Start = 9 × 60 + 0 = 540 min
Gross = 1050 − 540 = 510 minutes (8h 30m)
Net = 510 − 30 = 480 minutes = 8 hours = 8.00 decimal
Converting Minutes to Decimal Hours for Payroll
Payroll systems use decimal hours, not clock hours. You cannot multiply clock time directly by an hourly rate. 7 hours 45 minutes is NOT 7.45 hours — it is 7.75 hours. The conversion is: Decimal Hours = Hours + (Minutes ÷ 60).
| Clock Time | Minutes | Decimal Hours | Pay at $20/hr |
|---|---|---|---|
| 7h 00m | 420 | 7.00 | $140.00 |
| 7h 15m | 435 | 7.25 | $145.00 |
| 7h 30m | 450 | 7.50 | $150.00 |
| 7h 45m | 465 | 7.75 | $155.00 |
| 8h 00m | 480 | 8.00 | $160.00 |
| 8h 20m | 500 | 8.33 | $166.60 |
| 9h 45m | 585 | 9.75 | $195.00 |
Common Work Shift Durations
| Shift | Gross Hours | Less 30 min break | Net Decimal |
|---|---|---|---|
| 9:00 AM – 5:00 PM | 8h 00m | 7h 30m | 7.50 |
| 8:00 AM – 4:30 PM | 8h 30m | 8h 00m | 8.00 |
| 7:00 AM – 3:00 PM | 8h 00m | 7h 30m | 7.50 |
| 10:00 PM – 6:00 AM | 8h 00m | 7h 30m | 7.50 |
| 6:00 AM – 6:00 PM | 12h 00m | 11h 00m | 11.00 |
How Overnight Shifts Work
When your end time is earlier than your start time, the shift crosses midnight into the next calendar day. The calculator automatically handles this by adding 24 hours to the end time before calculating the difference. A 10:00 PM to 6:00 AM shift is treated as 10:00 PM to 30:00 (6:00 AM next day), giving 8 hours. Without this adjustment, the result would be negative — a common mistake when calculating overnight shifts manually.
FLSA Break and Overtime Rules
Under the Fair Labor Standards Act, rest breaks of 20 minutes or less must be counted as paid work time. Meal breaks of 30 minutes or more where the employee is completely relieved of duties are unpaid and should be deducted. Overtime kicks in at 40 hours per workweek at a rate of at least 1.5 times the regular pay rate. Some states (California, Alaska, Nevada) also require daily overtime for hours beyond 8 in a single day.
💡 Payroll Tip: Always use decimal hours for pay calculations. Multiply decimal hours by your hourly rate directly. For example: 38.75 hours × $22.50/hr = $871.88. Never use clock format (38:45) in multiplication — the result will be wrong. Most timekeeping software rounds to the nearest quarter-hour (0.25) for payroll purposes.
Frequently Asked Questions
Convert both times to total minutes since midnight (hours × 60 + minutes). Subtract start from end. Convert back: divide by 60 for hours, use the remainder for minutes. Example: 9:00 AM (540 min) to 5:30 PM (1050 min) = 510 minutes = 8 hours 30 minutes. If end is before start, add 1440 minutes to handle overnight shifts.
Add 1440 minutes (24 hours) to the end time when end is before start. Example: 10:00 PM to 6:00 AM. 10 PM = 1320 min; 6 AM = 360 min. Since 360 < 1320, add 1440: 360 + 1440 = 1800 min. Difference = 1800 − 1320 = 480 minutes = 8 hours. This calculator handles overnight shifts automatically.
Decimal Hours = Hours + (Minutes ÷ 60). Examples: 7h 30m = 7.50, 7h 45m = 7.75, 8h 20m = 8.33. This is critical for payroll because you multiply decimal hours by the hourly rate directly. 7h 45m at $20/hr = 7.75 × $20 = $155. Using 7.45 instead of 7.75 would give the wrong answer.
9 AM to 5 PM is exactly 8 hours. 9:00 AM = 540 minutes, 5:00 PM = 1020 minutes. Difference = 480 minutes = 8 hours. If you take a 30-minute unpaid lunch break, net work time is 7.5 hours. At $18/hour, 8 gross hours = $144 but with lunch deducted, you are paid for 7.5 hours = $135.
8 AM to 4 PM is exactly 8 hours. 8:00 AM = 480 minutes since midnight, 4:00 PM = 960 minutes. 960 − 480 = 480 minutes = 8 hours. This is one of the most common full-time shift patterns. With a 30-minute unpaid lunch break, billable hours are 7.5 hours per day, 37.5 hours per week.
7 hours 30 minutes = 7.50 decimal hours. 30 ÷ 60 = 0.50. Other quick conversions: 15 min = 0.25, 20 min = 0.33, 30 min = 0.50, 45 min = 0.75. Full chart: 7h 00m = 7.00, 7h 15m = 7.25, 7h 30m = 7.50, 7h 45m = 7.75, 8h 00m = 8.00.
Subtract the break duration (in minutes) from the gross minutes between start and end times. Example: 9:00 AM to 5:30 PM = 510 gross minutes. Minus 30-minute lunch = 480 net minutes = 8 hours. Only subtract unpaid breaks (typically 30 minutes or more). Short rest breaks of 20 minutes or less are paid time under FLSA and should not be deducted.
A standard US full-time work week is 40 hours (8 hours/day, 5 days). The FLSA requires overtime pay at 1.5x the regular rate for hours beyond 40 in a workweek. Part-time is typically under 30–35 hours. Some employers define full-time as 32 hours. For ACA health insurance purposes, full-time is defined as 30 or more hours per week.
For federal FLSA: add all hours worked in the workweek (Sunday to Saturday). Hours above 40 are overtime at 1.5x rate. California also requires daily overtime: over 8 hours/day = 1.5x, over 12 hours/day = 2x. Calculate regular pay first (up to 8 hrs/day or 40 hrs/week), then multiply excess hours by the overtime multiplier.
Clock hours use base-60 (60 minutes = 1 hour). Decimal hours use base-10 (0.5 hours = 30 minutes). They look similar but behave differently in math. 7:30 × $20 = $150 only works if you interpret 7:30 as 7.5 (decimal), not 7 hours and 30 minutes. Always convert to decimal before multiplying by a rate. Most payroll systems display hours in clock format but calculate in decimal.
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