The exact span between two times.
Handy for shifts, billing, and travel math. If the end time is earlier than the start and "next day" is off, the calculator assumes you meant the following day anyway — most real questions (a shift that crosses midnight) work that way; the checkbox makes it explicit.
How do I calculate hours worked minus lunch? Run the shift through once (start to end), then subtract the break length with a second pass — or subtract the break in minutes from the total minutes shown.
Does it handle seconds? Yes, if your browser’s time fields show seconds (the step is set to 1 second). Totals are also given in decimal hours for timesheets.