Dates & Time

Add Time Calculator (Add or Subtract Hours & Minutes)

Start with a time, then add or subtract hours, minutes, and seconds. It shows the result in both 24-hour and 12-hour form and tells you if the clock crossed into the next day.

How to use
  1. Enter the start time.
  2. Enter the hours, minutes, and seconds to add or subtract.
Quick add
Result time (24-hour)
11:30:00

11:30 AM

Day rollover
same day
Duration applied
2h 30m 0s
Duration (min)
150
Duration (h)
2.5
Date math uses your inputs as given; check time-zone and leap-year edge cases.
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How it's calculated

result = start time ± (h×3600 + m×60 + s)

start time and duration are converted to seconds, added or subtracted, then wrapped within 24 hours. Day roll-over = floor(total ÷ 86400); 86400 = seconds in a day.

Common questions

What time is 3 hours 30 minutes after 11:00 PM?

2:30 AM the next day. The calculator flags the rollover past midnight for you.

Can I subtract time as well as add it?

Yes. Switch to subtract and the same hours and minutes count backward from the start time.

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