Date Duration Calculator

Calculate the exact number of days, weeks, and months between two dates.

Working out timelines, notice periods, deadlines, and how long until an event.

How to use it

  1. Pick a start date

    Choose the first date with the date picker.

  2. Pick an end date

    Choose the second date; it should be on or after the start date.

  3. Read the duration

    See the breakdown in years, months, and days, plus total days and weeks — and toggle "include the end day" for inclusive ranges.

Why use this tool?

Working out exactly how long is between two dates is deceptively hard to do by hand. Months have 28 to 31 days, leap years add a day, and "about three months" is not good enough when you are counting a notice period, a contract term, or the days until a deadline. Miscount by even a day and you can miss a cut-off or misstate a duration on a form. This calculator gives you the precise gap between any two dates instantly: an exact breakdown in years, months, and days, plus the totals in days and weeks. Pick the start and end dates and read the result, with an option to include the end day for inclusive ranges. It uses real calendar dates, so leap years and varying month lengths are handled automatically, and everything is calculated in your browser with nothing stored. No sign-up, no limits.

Common use cases

Project timelines

Measure how long a project ran, or how many days remain until a deadline.

Notice & contracts

Count notice periods, probation/trial periods, and contract lengths exactly.

Countdowns

Work out how many days until a wedding, holiday, launch, or exam.

Billing & leave

Count billable days, rental periods, or days of annual leave between two dates.

Anniversaries & milestones

See how long it has been since a start date in days, weeks, months, and years.

Frequently asked questions

Does it count leap years correctly?

Yes. The calculation uses real calendar dates, so February 29 and varying month lengths are handled automatically.

What does “include the end day” do?

It adds one day so both the start and end dates are counted — useful for inclusive ranges like rental or billing periods.

Is the years/months/days breakdown exact?

Yes — it counts full calendar months and the remaining days rather than averaging, so the breakdown is exact.

Why might the standalone “months” total look approximate?

The total-months figure is based on average month length for convenience; the years/months/days breakdown is the precise calendar value.

Can I measure to a future date?

Yes. Set a future end date to count down the days, weeks, and months remaining.

How is this different from the Age Calculator?

They share the same maths; the Age Calculator is framed around a birth date and next birthday, while this one measures any two dates.

Are my dates uploaded?

No. The day, week, and month counts are computed right in your browser.

Is it free?

Yes — calculate any number of date ranges for free, with no sign-up.

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