Skip to content
DayUtils

Date Difference Calculator – Days Between Dates and Date Adder

Find out exactly how many days, weeks, months and years there are between two dates, or add and subtract days, weeks, months and years from a date. The calculator handles leap years and month ends correctly and also counts weekdays.

Loading tool…

How to use the date difference calculator

To count the time between two dates:

  1. Choose Days between dates.
  2. Pick the From and To dates. The start date begins as today.
  3. Tick Include the end date if you want to count both ends.

You’ll see the difference in years, months and days, the total number of days, weeks and days, total months, weekdays, hours and minutes.

To find a date in the future or past:

  1. Choose Add or subtract time.
  2. Pick the start date, choose Add or Subtract, and enter years, months, weeks and days.

How the calculation works

The number of days is simply the gap between the two dates on the calendar:

Days = End date − Start date (+ 1 if the end date is included)

Years, months and days are counted by stepping forward whole calendar months from the start date, then counting the days left over. This matches how people normally describe ages and contract lengths.

Worked examples

  • 1 January 2026 to 1 January 2027 = 365 days = 52 weeks and 1 day = 1 year.
  • 31 January 2026 to 1 March 2026 = 29 days = 1 month and 1 day.
  • 8 November 2026 + 90 days = 6 February 2027.
  • 29 February 2024 + 1 year = 28 February 2025.

Leap years

A year is a leap year if it divides by 4, except century years, which must divide by 400. So 2024 and 2028 are leap years, 2100 isn’t, and 2000 was. Leap years have 366 days, with 29 February as the extra day. The calculator applies these rules automatically.

Everyday uses

  • Countdowns: days until a holiday, wedding, exam or due date.
  • Deadlines: 30, 60 or 90 days from an invoice or notice date.
  • Contracts and notice periods: how long a lease or job contract lasts.
  • Travel: nights in a hotel, or days left on a visa (check your visa’s own counting rule).
  • Projects: weeks between milestones.
  • Records: how long ago something happened.

Tips

  • For legal or financial deadlines, check whether the rules count calendar days or business days, and whether weekends and public holidays move the deadline.
  • If you need working days only, use the business days calculator.
  • For someone’s exact age on a given date, the age calculator is designed for that.

To see which weekday a date falls on, try the day of the week calculator, or count down live with the countdown timer.

Frequently asked questions

How many days are there between two dates?

Subtract the earlier date from the later one. The calculator does this exactly, including leap years, and shows the result in days, weeks, months and years. For example, from 1 January to 31 December 2026 is 364 days, or 365 if you include the end date.

Should I include the end date?

It depends on what you’re counting. The time between two dates usually excludes the end date. If you’re counting days of a trip, a hotel stay or a contract that runs “from” one date “to” another inclusive, tick “Include the end date” to add one day.

How are months counted?

As whole calendar months. From 31 January to 1 March is 1 month and 1 day, because one month after 31 January is the last day of February.

What date is 90 days from today?

Switch to “Add or subtract time”, leave the start date as today and enter 90 days. The calculator shows the date and the weekday.

What happens when I add a month to 31 January?

The result is the last day of February (28th, or 29th in a leap year), because February has no 31st. Adding a year to 29 February likewise gives 28 February in a normal year.

Does it count weekends?

The main result counts every calendar day. The weekdays figure shows how many Mondays to Fridays fall in the period. For holidays as well, use the business days calculator.

Related tools

Last updated: