Time calculation guide

How to Calculate Time

Time is usually written in base 60, not base 10. That means 60 seconds make one minute, and 60 minutes make one hour. The easiest way to avoid mistakes is to convert everything to seconds first, do the math, then convert the result back.

Try a simple time calculator

Enter two times in HH:MM:SS format, choose an operation, and calculate the result.

First time Operation Second time or number

1. Convert the time to seconds

Use this formula: total seconds = hours x 3600 + minutes x 60 + seconds.

For example, 2:30:15 becomes 2 x 3600 + 30 x 60 + 15 = 9,015 seconds.

2. Perform the operation

Once each value is in seconds, you can add, subtract, multiply, or divide just like normal numbers.

Example: 2:30:15 + 1:45:30 = 9,015 + 6,330 = 15,345 seconds.

3. Convert the result back

Divide by 3600 to get hours. Use the remainder to calculate minutes and seconds.

15,345 seconds = 4 hours, 15 minutes, 45 seconds, or 04:15:45.