Time Duration Calculator

A time duration calculator measures how much time elapses between two specific moments. You enter a start date and time and an end date and time, and the tool reports the gap broken down into several units at once: total seconds, total minutes, total hours, total days, weeks, and a human-readable summary. This is more useful than a single figure, because a timesheet entry often needs hours and minutes while a project log might want total days. The calculation works on wall-clock time in your browser's local timezone, which is the correct default for everyday tasks like billing and shift tracking. The most important subtlety is daylight saving time. Because durations are measured in local wall-clock time, a range that crosses a spring-forward or fall-back transition will differ from the naive clock arithmetic by an hour: an overnight shift that appears to be eight hours on the clock can be seven or nine real hours across a DST change. The tool reflects the true elapsed time. It also handles overnight and multi-day ranges cleanly, so a shift that starts at 10 PM and ends at 6 AM the next morning is correctly reported as eight hours rather than producing a negative or wrapped result. If you accidentally enter an end that is earlier than the start, the duration is shown as negative with a clear warning so you can swap the inputs. Everything is computed locally, so the dates and times you enter, which can reveal work schedules or personal events, are never uploaded or logged.