Date Difference Calculator

A date difference calculator measures the span between two calendar dates and reports it in multiple units at once: total days, weeks, months, and years. Pick a start date and an end date, and the tool returns the gap using the browser's native date engine, which correctly accounts for leap years and the varying lengths of each month. This avoids the classic manual mistake of multiplying months by 30, which drifts further off the more months you span. The result distinguishes between a whole-calendar reading, where 15 January to 15 March is exactly two months, and a raw total-days reading, which is what matters for interest, deadlines, or notice periods. An optional business-days mode counts only Monday through Friday, excluding weekends, which is the figure most contracts, SLAs, and shipping estimates actually use. Note that this mode skips weekends but does not know about public holidays, which differ by country and region, so for a strict working-day count you may need to subtract local holidays yourself. A common edge case is the inclusive-versus-exclusive question: the number of nights between two dates is one less than the number of days you are physically present, which is why a hotel stay from Monday to Wednesday is two nights but touches three calendar days. The tool reports the plain difference so you can apply whichever convention your situation needs. All computation happens in your browser, so project timelines, contract dates, and personal milestones stay on your device. Use it for project planning, counting down to a deadline, billing by elapsed days, or working out how long ago an event happened.