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8:30 to 5:15 minus a 30-minute lunch = 8h 15m = 8.25 decimal hours — the number payroll actually wants.
The shift math everyone does badly in their head: end minus start, minus the break, in both human (8h 15m) and payroll (8.25) formats. Overnight shifts wrap midnight automatically — 22:00 to 06:30 is 8.5 hours, not an error.
Shift workers use it nightly: 8:30 to 5:15 minus 30 for lunch is 8h 15m = 8.25 decimal hours — the number payroll actually wants. Overnight wraps handled.
Because wage math needs decimals: 8h 45m × $24.50 is not calculator-friendly until it is 8.75 × $24.50 = $214.38. The conversion table every worker should know: 15 min = 0.25, 30 min = 0.50, 45 min = 0.75 — and the awkward ones, 10 min = 0.167, 20 min = 0.333. Employers round differently, and the method matters to your check: quarter-hour rounding (nearest 0.25) is the legal common standard; 7-minute grace rules round 7:53 to 8:00; and some systems truncate, which costs workers minutes daily. Federal law requires the rounding to even out over time — always rounding against the employee is a wage violation. Check your stub: the decimal conversion on this page is the exact one honest payroll uses.
They wrap through midnight: 22:00 to 06:30 is 8.5 hours — this calculator detects the wrap when the end is earlier than the start. Where overnight math gets legally interesting: the FLSA workday boundary decides which day overtime lands on, most states split the shift at midnight or at the employer's declared workday start, and California daily overtime (over 8 hours in a workday) can trigger mid-shift. Shift differentials add a layer: night premiums of 5–15% typically apply to hours after a set time (often 11 PM), so a 10 PM–6 AM shift might earn base pay for 1 hour and premium for 7. When the paycheck looks wrong on an overnight, the workday-boundary definition in your handbook is the first thing to check.
Federal law: short breaks (5–20 minutes) are paid work time; bona fide meal periods (30+ minutes, fully relieved of duty) can be unpaid. The traps: "relieved of duty" is literal — answering one work call during lunch converts the whole period to paid time in most interpretations; working through lunch at your desk is paid time regardless of what the timesheet says; and several states (California, New York, others) mandate meal breaks by shift length with premium-pay penalties when skipped. Smoke-break math adds up fast: four 10-minute breaks daily is 0.67 paid hours — 2.9 hours a week. If your timesheet auto-deducts 30 minutes whether or not you ate, that deduction is only legal when the meal break was genuinely duty-free — a common and litigated wage-theft pattern.