Date & Time Calculators

Date and time math gets fiddly fast — months have different lengths, leap years sneak in, and weekday counts depend on where exactly the range starts and ends. The calculators in this category handle the bookkeeping so you don't have to: counting days between two dates, splitting a span into years/months/days, separating working days from weekends, and converting to alternative units like weeks or hours. Every tool uses ISO 8601 dates and the proleptic Gregorian calendar, runs in your browser, and shows enough of the breakdown that you can sanity-check the answer. Pick the calculator that matches your question, enter the dates, and read off the result.