Date Difference Calculator

About the Date Difference Calculator

Enter two dates and this calculator returns the span between them — in total days, in weeks and days, and as a calendar breakdown of years, months and days. Working days are counted separately, with weekend days shown alongside.

Two different measures are given because both are useful and they are not interchangeable. The total days figure is a plain count. The years, months and days breakdown follows the calendar, so a "month" is however long that particular month was.

Order does not matter; the tool sorts the dates itself. Use it for project timelines, notice periods, how long you have lived somewhere, or how many days remain until a deadline.

How to use the Date Difference Calculator

1. Pick the from and to dates.
2. Select Calculate the difference.
3. The headline counts whole days between them; the inclusive figure counts both ends.
4. Business days exclude Saturdays and Sundays.
5. Entering the dates the wrong way round is handled automatically.

The two ways to measure a span

Do you count both the start and end date?

It depends on the convention, and the answer changes your result by one day. Both are in common use:

• Exclusive counting — count the days between the dates. From 1 March to 5 March is 4 days. This is what the calculator reports.
• Inclusive counting — count both endpoints. From 1 March to 5 March is 5 days. Common for hotel nights, hire periods, event durations and some legal deadlines.

To get the inclusive figure, add one to the total shown. Where a contract or a legal deadline is involved, check which convention applies — a one-day error at the end of a notice period can matter a great deal.

Why months are awkward to count

Because they are not a fixed length. A month can be 28, 29, 30 or 31 days, so "how many months between these dates" has no single answer unless you say how you are counting.

Rows two and four make the point. February and July are both "one month" and "six months" respectively in calendar terms, yet the day counts differ. The calendar breakdown is what people mean in ordinary speech; the total-days figure is what you want for anything being counted precisely.

Working days and the 1.4 rule

The calculator counts Monday to Friday within your span and reports weekend days separately. A full week contains 5 working days out of 7, so calendar spans convert to roughly 71% working days — or, going the other way, working days take about 1.4 times as long in calendar terms.

Public holidays are not deducted. Holiday calendars differ by country, region and year, so building one in would give most users a wrong answer. Most countries observe 8 to 15 public holidays annually — subtract those manually where the deadline matters.

What this tool is for

• Project timelines — elapsed and working days between milestones.
• Notice and probation periods — check the exact end date.
• Countdowns — days remaining to a deadline, a wedding or a trip.
• Residency and employment records — how long a period actually lasted.

To move forward or back from a single date instead, use the date calculator. To compare two people's ages, use the age difference calculator.

How to calculate days between two dates

Count the days left in the first month, add the full months in between, then add the days in the last month. From 15 March to 10 June: 16 days left in March, 30 in April, 31 in May and 10 in June gives 87 days. This tool does that instantly, and it shows the difference between two dates in weeks, months and years as well.

Weeks between two dates

The result shows Weeks and days for you. To do it by hand, take the total days and divide by 7. The whole number is the weeks. The remainder is the extra days.

Months between two dates

Count whole calendar months first. Then count the leftover days. That is what the years, months, days line does. A decimal figure such as "8.2 months" is only an estimate, because months vary in length.

• 1 March to 1 June — exactly 3 months (92 days).
• 15 January to 10 April — 2 months and 26 days.
• 31 January to 28 February — 28 days, but most people call it one month.

Years between two dates

For long spans, such as years of service or time at an address, the years figure matters most. Count full years from the start date, then months, then days.

Calculate duration between two dates, in any unit

The same span can be written many ways. Pick the unit your form or plan asks for.

Need the time between two clock times on the same day instead? The time calculator handles hours and minutes, including night shifts.

Other ways to use this calculator

• Days between dates — how many days between two dates, with or without the end date.
• Working days calculator — the result includes the number of business days, skipping weekends.
• Duration between dates — the result also shows weeks between dates and months between dates.

Frequently asked questions