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Date Difference Calculator

Calculate exact days, business days, weeks, months, and years between two dates or add/subtract time from a date.

Runs in your browser. Nothing you add is uploaded.

What the Date Difference Calculator does

Counting the gap between two dates by hand means tracking month lengths and leap years, which is exactly the sort of thing people get wrong by a day or two. This calculator returns the difference in years, months, and days, plus the totals in days, weeks, and months — and separately counts business days, which is what contracts and project plans usually actually mean.

How to calculate the days between two dates

  1. Enter the start date.
  2. Enter the end date. Order does not matter — the result is the absolute difference.
  3. Read the breakdown in years, months, and days, and the totals underneath.
  4. Use the business-day count when weekends should be excluded.

The Date Difference Calculator runs entirely in your browser — nothing you enter is uploaded, stored, or logged.

When to use it

Tracking a notice or deadline period

Contractual notice periods, statutory deadlines, and warranty windows are counted in days. An off-by-one error here has real consequences.

Planning a project timeline

Working days matter more than calendar days for delivery estimates, since a 30-day span contains roughly 21 working days.

Counting down to an event

Days until a launch, a wedding, or an exam — with weeks shown alongside, which is often the more useful unit for planning.

Good to know

  • Decide whether your count is inclusive of both endpoints. A 'ten-day period' starting Monday may end on the second Wednesday or the second Thursday depending on the convention in force.
  • Business-day counts here exclude weekends but not public holidays, which vary by country and region.
  • Total months and the years-months-days breakdown will not match arithmetically, because months differ in length. Both figures are correct.
  • For deadlines that matter legally, confirm which counting convention the governing document specifies.

Frequently asked questions

How does business day calculation work?

Iterates through the range and excludes Saturdays and Sundays.

Does the calculation include both the start and end dates?

The difference is exclusive by default — from 1 March to 8 March is 7 days. If your context counts both endpoints, as many contractual and rental periods do, add one to the result. Which convention applies is a question about your document, not about the arithmetic.

How are leap years handled?

Automatically, using real calendar arithmetic. Every 29 February falling between the two dates is included in the day count. Using a fixed 365-day year to estimate long spans undercounts by roughly one day every four years.

How are business days counted?

By excluding Saturdays and Sundays from the total. Public holidays are not excluded, because they vary by country, state, and sometimes industry — subtract those separately for your own calendar.

Why do the months and days figures not add up neatly?

Because months have between 28 and 31 days. '2 months and 15 days' is a calendar-based description, while the total-days figure is an exact count. They describe the same interval in two different units and cannot be reconciled by simple multiplication.

Can I calculate a difference across time zones?

This calculator works on calendar dates rather than timestamps, so time zones do not affect it. For precise durations between moments in different zones, you need a time-aware calculation instead.

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