Eight hours. With a 30-minute lunch break, 7.5 hours. With a full hour for lunch, 7 hours. The 8-to-4 shift is one of the most common work schedules in healthcare, manufacturing, and government — and it shares its math with several other popular shifts. Here's the full breakdown.
8 AM to 4 PM = 8 clock hours.
The 8-to-4 shift is the dominant schedule in several industries:
| Shift | Total clock hours | With 30-min lunch | With 60-min lunch |
|---|---|---|---|
| 7 AM – 3 PM | 8.0 | 7.5 | 7.0 |
| 7 AM – 4 PM | 9.0 | 8.5 | 8.0 |
| 7:30 AM – 4 PM | 8.5 | 8.0 | 7.5 |
| 8 AM – 3 PM | 7.0 | 6.5 | 6.0 |
| 8 AM – 4 PM | 8.0 | 7.5 | 7.0 |
| 8 AM – 4:30 PM | 8.5 | 8.0 | 7.5 |
| 8 AM – 5 PM | 9.0 | 8.5 | 8.0 |
| 8:30 AM – 5 PM | 8.5 | 8.0 | 7.5 |
| 9 AM – 5 PM | 8.0 | 7.5 | 7.0 |
| 9 AM – 6 PM | 9.0 | 8.5 | 8.0 |
| 10 AM – 6 PM | 8.0 | 7.5 | 7.0 |
| 10 AM – 7 PM | 9.0 | 8.5 | 8.0 |
For an 8-to-4 shift Monday through Friday with 30-min unpaid lunches: 7.5 hrs/day × 5 days = 37.5 hours/week. That's under the 40-hour federal overtime threshold, so no overtime owed.
For an 8-to-5 shift (which is 8 hours worked with a 1-hr lunch, or 8.5 hrs worked with a 30-min lunch): 5 days × 8 hours = exactly 40 hours/week, sitting right at the OT threshold.
The simple formula:
Total clock hours = (End time in 24-hour format) − (Start time in 24-hour format)
For shifts that cross noon (start AM, end PM), the trick is that PM hours past 12 need 12 added in math. 9 AM to 5 PM = 17 − 9 = 8 hours. 11 AM to 3 PM = 15 − 11 = 4 hours.
For shifts like 11 PM to 7 AM (night shift), the math wraps:
Or simply: hours until midnight (1 hour) + hours after midnight (7 hours) = 8 total.
The half-hour difference between a 7.5-hour and 8-hour shift compounds significantly. Over a year (50 working weeks), it adds up to 125 hours — about 3 full work weeks. If you're negotiating between two jobs, a 7.5-hour shift at the same hourly rate is meaningfully better.
When job postings say "8 to 5," they typically mean 8 hours of paid work with a 1-hour unpaid lunch — totaling 9 hours of clock time at the office. "9 to 5" historically meant 8 hours of work + 1-hour lunch = 9 clock hours, but in modern usage it often means literally 9 AM to 5 PM (8 clock hours).
If your employer pays for lunch breaks (rare but exists in some healthcare, transit, and union jobs), an 8-to-4 shift with paid lunch = 8 hours of pay. The lunch break doesn't reduce paid time.
The Hours Calculator handles any start/end combination including breaks, overnight shifts, and weekly aggregation. The Quick tab is best for single-shift math.
Published May 2026. Spot an error? Email contactus@calculatehours.net.