Time & Elapsed Time Calculator
Figure out exactly what time it will be, or calculate how much time has passed between two events!
* If the End Time is earlier than the Start Time, we assume it's the next day!
Time Result
How we solved it:
Mastering Time Math
The Base-60 Trap!
Most math we do uses "Base-10". When we add 9 + 2, we go past 10, carry the 1, and make 11. But clocks use Base-60!
Because there are exactly 60 minutes in an hour, you can never have a time like "3:75". Once the minutes hit 60, they magically transform into 1 full hour, and the minutes reset back to 00.
Borrowing in Time Subtraction
When calculating elapsed time using vertical subtraction, you might need to "borrow" if the bottom minutes are larger than the top minutes.
Rule: When you borrow 1 hour, you must add 60 minutes to your minute column, NOT 10 or 100!
The "Number Line" Strategy
For students in Classes 3 to 5, calculating elapsed time is much easier using a mental "Number Line". We jump in friendly chunks! Let's say we want to find the time from 8:15 AM to 11:30 AM:
1. Jump the Mountains (Hours)
Jump 3 full hours from 8:15 AM. You land on 11:15 AM. (That's 3 Hours).
2. Jump the Hills (5 or 10 Mins)
Now jump from 11:15 AM to 11:30 AM. That's a jump of 15 Minutes.
3. Add it up!
Total time passed: 3 Hours and 15 Minutes. Easy!