Find the duration between two clock times, or add and subtract a precise amount of time. Overnight ranges and day rollover are reported clearly.
The calculator works in whole seconds and keeps the day offset separate from the displayed 24-hour clock time, so a result that crosses midnight is never hidden.
Enter two 24-hour clock times to get the elapsed hours, minutes, and seconds. When an end time is earlier than the start, the overnight option treats it as a time on the following day.
Add or subtract any non-negative number of hours, minutes, and seconds. The displayed clock result wraps to a 24-hour day while a separate day offset preserves the complete answer.
Related tools: Time Unit Converter · Stopwatch · Date Calculator