Comprehensive Calculator Guide
This calculator adds two durations in hours and minutes, or subtracts one from the other, carrying minutes over 60 into hours. 2:45 + 1:30 = 4 h 15 min, and 8:00 − 2:20 = 5 h 40 min. Use it to total working hours, study time or trip legs.
Why time doesn't add like decimals
An hour has 60 minutes, not 100, so adding 2.45 + 1.30 as decimals gives a wrong 3.75. Add the minutes on their own (45 + 30 = 75 = 1 h 15 min) and carry the hour: 4 h 15 min.
When subtracting, borrow an hour as 60 minutes if needed: 8:00 − 2:20 is 7:60 − 2:20 = 5:40. A longer second duration gives a negative result.
How to Use
- 01Enter the first duration's hours and minutes.
- 02Choose add or subtract.
- 03Enter the second duration.
Formula Used
Result in minutes = (h1 × 60 + m1) ± (h2 × 60 + m2)Practical Examples
Example 1: adding
2:45 + 1:30 = 4 h 15 min (4.25 h).
Example 2: subtracting
8:00 − 2:20 = 5 h 40 min.
Important Tips
- 1:30 is an hour and a half, which is 1.5 hours, not 1.3.
Common Mistakes to Avoid
- Adding times as decimal numbers.
- Leaving 75 minutes unconverted.
Frequently Asked Questions
- How do I add hours and minutes?
- Add minutes and hours separately and carry every 60 minutes into an hour.
- How do I subtract time?
- Convert both to minutes, subtract, then convert back.
- Can the result be negative?
- Yes, if the second duration is longer.