Time Duration Calculator

How long did something take? This time duration calculator finds the exact elapsed time between any start and end time — down to the second — and handles overnight durations, AM/PM conversions, and multiple time formats.

How to Use This Calculator

1. Enter the start time (in 12-hour or 24-hour format).
2. Enter the end time.
3. Click Calculate to see the duration in hours, minutes, seconds, and as a decimal.

Example Calculations

Start: 10:15 AM | End: 3:45 PM → Duration: 5 hours 30 minutes (5.5 hours)

Start: 11:30 PM | End: 7:00 AM → Duration: 7 hours 30 minutes (overnight)

Start: 09:00:00 | End: 09:45:32 → Duration: 0 hours 45 minutes 32 seconds

Decimal Hours Conversion

• 5 hours 30 min = 5.5 hours
• 5 hours 45 min = 5.75 hours
• 5 hours 20 min = 5.33 hours
• Use decimal hours for pay calculations (hours × hourly rate)

Common Uses

• Timing experiments, races, or events
• Calculating billable hours (attorneys, consultants, freelancers)
• Measuring cooking, exercise, or study session durations
• Log duration for time tracking software

Frequently Asked Questions

How do I calculate duration across multiple days?

Use our Date Calculator for multi-day spans. For time within a day or a single overnight period, this duration calculator handles it directly.

How do I convert duration to decimal for pay?

Minutes ÷ 60 = decimal hours. 2 hours 45 minutes = 2 + (45/60) = 2.75 hours. Multiply by your hourly rate for pay.

Conclusion

Time duration is one of the most frequently needed calculations — for work, billing, sports, and daily life. This calculator handles all time formats and overnight crossings accurately, giving you the result in both HH:MM:SS and decimal format.

Related: Time Calculator | Hours Calculator | Date Calculator