📅 Dates

Date Difference Calculator

Calculate the difference in days, weeks, months and years between two dates. Instant result in the browser.

Start date

End date

How is the difference calculated?

It starts from the difference in milliseconds, computed with UTC arithmetic. That choice sidesteps the errors that daylight saving time (DST) changes would introduce. The value is then converted into days, weeks, approximate months and years.

None of this leaves your browser. Your dates are never sent to any server.

How many days between two dates?

Counting days one by one on a calendar is where almost everyone slips up, especially when the span crosses months of different lengths or lands on a leap year. Here you pick the start and end dates and see the exact difference, with no risk of skipping a day or counting an extra one.

The result shows up in several units at once (days, weeks, months and years), and you use whichever makes sense. You can work out contract length, a delivery deadline, age in days, a countdown to an important date, or how long ago something happened.

The calculation runs entirely in the browser and sends nothing to any server. Change either date and the result adjusts in the same instant.

Frequently asked questions

Does the start date count as one of the days?

No. What you see is the gap between the two dates, so 1 January to 2 January returns 1 day, not 2. When you need an inclusive count, such as hotel nights, vacation days or a deadline that counts its first day, add 1 to the number shown. Legal deadlines follow their own rule and usually exclude the starting day.

Why do the months and years come out with decimals?

Because every unit is derived from the same day count. Weeks are days divided by 7, months use an average of 30.44 days and years use 365.25 days so leap years average out. These are statistical approximations rather than calendar months: 31 January to 28 February reads as roughly 0.9 months even though the calendar calls it one full month.

Does it skip weekends and holidays?

No. It counts calendar days, weekends and holidays included, which is the basis for contracts, warranties and most civil deadlines. Business-day counting needs a different tool, since this one never consults a holiday calendar. Entering the dates in reverse order works too: the difference simply comes back with a minus sign.

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