Time Duration Calculator
Calculate Exact Duration Between Two Times
Calculating work hours, billing time, or shift duration by hand is error-prone — especially for overnight shifts or schedules with break deductions. This calculator gives you the precise net duration after subtracting break time, expresses it in decimal hours for payroll compatibility, and shows where your shift falls within the 24-hour day visually.
How to Use This Calculator
Enter your start time and end time, then add any break duration in minutes. If your shift crosses midnight (e.g., 10 PM to 6 AM), select "Yes" for overnight shift. Hit Calculate Duration to see net work time, total time, decimal hours, and the full 24-hour breakdown.
How the Calculation Works
Example: 9:00 AM to 5:30 PM with a 30-minute break. Total = 510 min (8.5 hr). Net = 510 − 30 = 480 min = 8.00 decimal hours.
Minutes to Decimal Hours Conversion
Payroll systems use decimal hours — 7 hours 45 minutes is 7.75, not 7.45. Divide the minutes portion by 60:
- 7 hr 15 min = 7.25 hr
- 7 hr 30 min = 7.50 hr
- 7 hr 45 min = 7.75 hr
- 8 hr 20 min = 8.33 hr
- 8 hr 40 min = 8.67 hr
Overnight Shifts
When end time is earlier than start time, the calculator automatically assumes an overnight shift. A 10 PM to 6 AM shift spans 8 hours — a straight subtraction gives a negative result, so the calculator adds 24 hours to the end time before calculating. Check "Yes (crosses midnight)" to ensure this is handled correctly if end time is later than start time but still spans midnight.
Frequently Asked Questions
Why does my paycheck show fewer hours than I calculated?
Most payroll systems round time in increments — typically to the nearest 6 minutes (0.1 hours) or 15 minutes. A shift from 8:54 AM to 5:08 PM might be recorded as 8:00 or 8:15, not 8:14. FLSA rules permit rounding if applied consistently and it doesn't systematically undercount employees. If you suspect consistent undercounting, compare your clock-in records to pay stubs over several periods.
How do I track hours for client billing with multiple breaks?
Run the calculator once per uninterrupted work segment and add the decimal totals. If you worked 9:00–12:30 (3.50 hr) and 1:00–5:45 (4.75 hr), total billable = 8.25 hours. Alternatively: use start-to-end with combined break time. 9 AM to 5:45 PM = 8 hr 45 min total, minus 30-min lunch = 8.25 hr net — same result either way.
How many hours is a typical work week?
A standard full-time week is 40 hours — 8 hours/day × 5 days. The FLSA defines overtime as any hours over 40 in a workweek, paid at 1.5× the regular rate. Some states (California, for example) also require daily overtime for more than 8 hours in a single day. Exempt salaried employees aren't subject to overtime requirements regardless of hours worked.
Can I use this for freelance billing?
Yes — enter start and stop times for each work session and note the decimal total. Multiply by your hourly rate. Use our Work Hours Calculator for tracking multiple sessions across a full week, or pair this with the Freelance Rate Calculator to ensure your hourly rate covers your target annual income.
What does the donut chart show?
The donut shows a full 24-hour day divided into three segments: blue = net work time, yellow = break time, grey = remaining off hours. It gives a visual sense of how much of the day a shift occupies. An 8-hour shift with a 30-minute break takes up about 35% of the full day. It's particularly useful for visualizing shift lengths and comparing different schedule options at a glance.