Time Duration Calculator

Working out how long something lasted from a start and end time sounds trivial until the math involves borrowing across the hour, or the event runs past midnight into the next day — a night shift that starts at 22:00 and ends at 06:00, a flight that departs late and lands the next morning, a movie marathon that started before midnight. Straight subtraction gives a negative number in exactly those cases, which is where people usually reach for a calculator instead of doing it in their head.

It's built for anything measured start-to-end in clock time rather than elapsed stopwatch time: shift lengths, meeting spans, how long a call lasted, or how much runway is left between now and an appointment. The overnight toggle handles the midnight-crossing case explicitly, so you don't have to mentally add 24 hours yourself.

The result is given three ways — hours and minutes, total minutes, and decimal hours — because different situations call for different units: decimal hours is what most timesheet and billing software expects, while hours-and-minutes is what you'd say out loud.