How to Calculate Time Duration
Calculating the duration between two times can be tricky, especially when crossing AM/PM boundaries or midnight. Our calculator handles this instantly.
Manual Calculation Formula
To calculate time duration manually:
- Convert to 24-hour format: e.g., 2:00 PM becomes 14:00.
- Subtract Start from End: Subtract the start minutes from end minutes, and start hours from end hours.
- Adjust for negatives: If minutes are negative, borrow 60 from hours. If hours are negative (overnight), add 24 to the end hour.
Example: 9:00 AM to 5:30 PM
- Convert: 9:00 to 17:30
- Subtract: 17 hours - 9 hours = 8 hours
- Subtract: 30 mins - 0 mins = 30 mins
- Result: 8 Hours 30 Minutes
Frequently Asked Questions
1. How do I calculate time across midnight?
If the end time is "smaller" than the start time (e.g. Start 10 PM, End 2 AM), you must add 24 hours to the end time value. For example, 2 AM becomes 26:00. Then subtract: 26 - 22 = 4 hours.
2. What formats does this calculator accept?
Our smart input accepts almost anything. You can type "9", "9am", "0900", "14:30", "2p". It will automatically detect 12-hour or 24-hour format.
3. How is this different from a time card calculator?
A time card calculator typically deducts unpaid lunch breaks and sums up a whole week. This tool is simpler—it strictly calculates the elapsed time between Point A and Point B without deductions.