Free calculators and unit converters for general and everyday use.
Our online tools will provide quick answers to your calculation and conversion needs. On this page, you can add/ subtract any number of hours or minutes to/ from a given clock time. Get answer to questions like "what time will it be in 8 hours?" "what time was it 45 minutes ago?"
Before we start the calculation, we convert the time value to 24-hour format.
Steps for adding time
e.g., what time will it be in 30 minutes?
Add the hours and the minutes separately. If the minutes are >= 60, subtract 60 from the minutes and add 1 to hours. If the hours are >= 24, set hours to "hours mod 24".
Steps for subtracting time
e.g., what time was it 16 hours ago?
Subtract the hours and the minutes separately. If the minutes are < 0, add 60 to the minutes and subtract 1 from hours. If the hours are < 0, add 24 and set it to "hours mod 24".
Convert the time back to 12-hour format at the end of calculation.