How to Calculate the Days Between Two Dates
Updated October 2026
Written by the Toolpuffin team. Tools in this guide are tested in the browser.
How many days until the holiday, how long since you started, how many working days before the deadline? Counting on a calendar is easy to get wrong by one day. This guide shows how to get the exact number and the choices that change it.
Count the days in three steps
- Enter the start date and the end date.
- Read the total days, and the split in years, months and days.
- Tick the end-date option if both days count.
Is the end date included?
This is the most common source of an off-by-one mistake. From Monday to Friday of the same week there are 4 days between the dates. If both Monday and Friday count, such as a hotel stay that includes both days, it is 5.
Decide before you count: are you measuring the distance between two moments, or the number of days covered?
Example
From 16 October 2026 to 25 December 2026 is 70 days: 15 days left in October, 30 in November and 25 in December. From 1 January 2026 to 1 January 2027 is 365 days, because 2026 is not a leap year.
Weekdays and working days
The count of weekdays is every Monday to Friday in the period. Public holidays are not taken out, because they differ per country and sometimes per region. If you need working days, subtract the holidays that fall in your period yourself.
Adding or subtracting time
To find the date 90 days from now, or 6 weeks before an event, use the add and subtract block. Months need care: a month does not have a fixed length. Adding one month to 31 January 2026 gives the last day of February, 28 February, because 31 February does not exist.
Leap years
A year is a leap year when it can be divided by 4, except for century years, which must be divisible by 400. So 2028 is a leap year, 2100 is not and 2000 was. A leap year has 366 days, with 29 February. The calculator takes this into account.
Dates for deadlines and contracts
Rules for counting days differ. A contract or a law may say whether the first day counts, whether weekends are skipped and what happens when the last day falls on a weekend. Use the calculator for the arithmetic, and check the wording of the agreement for the rules.
Privacy
The calculation is done in your browser. The dates you enter are not sent anywhere.