InfyCalculator
📅

Time Addition Across Midnight Calculator

Add hours and minutes to a clock time and get the correct result when it rolls past midnight — with the day offset and 24-hour form.

Start time
Add hours
Add minutes
Loading calculator…

How it works

total minutes = start time (in minutes from midnight) + hours × 60 + minutes · end time = total mod 1440 · day offset = ⌊total ÷ 1440⌋ (negative if the time goes back past midnight)

Clock arithmetic wraps at 24 hours, so 22:30 plus six hours is 04:30 the next day, not 28:30. This converts the start time to minutes past midnight, adds your hours and minutes, then takes the result modulo 1,440 (minutes in a day) for the clock time and divides by 1,440 for how many days it rolled over. Negative inputs subtract time and can roll back to the previous day, which is handy for working out start times from a deadline.

Worked example

Starting at 22:30 and adding 5 hours 45 minutes gives 1,695 total minutes. That is 1 day plus 255 minutes, so the end time is 04:15 (4:15 AM) the next day.

Frequently asked questions

How does it handle crossing midnight?

It reports the wrapped clock time plus a day offset. Adding enough time to pass midnight shows "+1 day" (or more); the clock value itself is always a valid 00:00–23:59 time.

Can I subtract time?

Yes — enter negative hours or minutes. Going back past midnight shows a −1 day offset, so you can find when something must start to finish by a set time.

What time formats can I enter?

A 24-hour HH:MM such as 22:30, or a 12-hour form with AM/PM such as "10:30 pm". The end time is shown in both 12-hour and 24-hour notation.

Related calculators

Add Time Calculator
Add or subtract durations in hours, minutes and seconds (HH:MM:SS, 1h 30m or days), as many as you need, and get the total as h m s, HH:MM:SS, minutes, seconds and decimal hours, plus the end time on the clock.
Time Duration Calculator
Work out the hours, minutes and seconds between two clock times — 24-hour or AM/PM, across midnight or several days, minus a break — or add or subtract a duration to find an end or start time.
Countdown Timer End Time Calculator
Enter a timer length in hours, minutes and seconds and a start time to see exactly when it finishes, to the second, with the end date and a next-day flag. Or work backwards: when to start a timer to finish on time, or how long to set it between two clock times. Repeating rounds with breaks, a reminder and checkpoints included.
Elapsed Time Between Two Times Calculator
Find the exact duration between a start and end time, including shifts that cross midnight, in hours and minutes.
Timesheet Calculator
Add up a week of work: same hours every day or a start and end time for each day, unpaid breaks, clock rounding, overtime (US 40-hour, California daily or Mexico rules) and gross pay.

This calculator is for educational purposes. Double-check important results before acting on them.