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Date & Age Calculator

Date Calculator

Count the days between two dates, or add and subtract days, weeks, months or years to find a new date.

What do you want to calculate?

Choose a start date and an end date to see the difference.

Quick date calculators

Common date calculations based on today's date.

Two ways to use the date calculator

Days between dates

Enter a start date and an end date to find how far apart they are. The answer is shown three ways: as years, months and days (the way you would say it out loud), as a total number of days and weeks, and as a split between weekdays and weekend days. Total months are given as an approximation, because months are not all the same length.

Add or subtract

Pick a start date and add or subtract any number of days, weeks, months or years. The result shows the exact date and which day of the week it falls on. For deadlines measured in working days, tick “Exclude weekends” or use the business days calculator.

Counting days: inclusive or exclusive?

Most date differences are measured exclusively: from Monday to Tuesday is one day. That is the default here. Some situations count both the first and last day: a hotel stay from the 1st to the 3rd is two nights, but a conference over the same dates runs for three days. Tick “Include the end date” whenever the last day should count too.

Days from today and days ago

Questions like “what is the date 90 days from today?” come up constantly: return windows, probation periods, visa stays, payment terms and project milestones are often set as a number of days. The quick calculators above answer the most common ones using today's date on your device. For any other number, use “Add or subtract”.

Adding months and years

Adding months keeps the same day of the month where possible: 15 January plus one month is 15 February. When the target month is shorter, the result moves to its last day, so 31 January plus one month is 28 February (or 29 February in a leap year). Adding a year to 29 February gives 28 February in a year that has no leap day.

Accuracy

The calculator works with whole calendar dates, not clock times, so daylight-saving changes and time zones never shift the answer by a day. It follows the Gregorian calendar for all dates, with leap years every four years except century years not divisible by 400.

Frequently asked questions

How do I calculate the number of days between two dates?

Choose “Days between dates”, enter a start date and an end date, and the result appears straight away. You get the total number of days, the same span in years, months and days, and how many of those days are weekdays or weekend days.

Does the calculator include the start date?

By default the count starts at the start date and stops before the end date, so 1 January to 2 January is 1 day. This is the usual way to measure a gap between two dates. If you need both dates counted — for example, the length of an event that runs from the 1st to the 2nd — tick “Include the end date”, which adds one day.

How many days are there between two dates?

It depends on the months and years in between, because months have 28 to 31 days and leap years have 366 days. The calculator counts each actual calendar day, so you don't have to work this out by hand.

How are leap years handled?

Every calculation uses the Gregorian calendar, where a year is a leap year if it is divisible by 4, except century years, which must also be divisible by 400. So 2024 and 2000 have a February 29, while 2025 and 1900 do not. February 29 is counted whenever it falls inside your range.

How are business days calculated?

Business days are Monday to Friday. When you compare two dates, the result shows how many of the counted days are weekdays and how many are Saturdays or Sundays. When adding or subtracting days, tick “Exclude weekends” to skip Saturdays and Sundays. Public holidays are not excluded, because they differ by country and region.

Can I calculate a date in the future?

Yes. Choose “Add or subtract”, pick a start date, choose Add, and enter an amount in days, weeks, months or years. The result shows the exact date and the day of the week. The quick calculators below the tool cover common cases like 30, 60 and 90 days from today.

Can I subtract days from a date?

Yes. In “Add or subtract”, choose Subtract and enter the number of days, weeks, months or years. This is useful for finding a date a set number of days ago, such as the start of a 90-day period.

What happens when I add a month to January 31?

February has no 31st, so the result moves to the last day of February — February 28, or February 29 in a leap year. The same rule applies to any month that is shorter than the starting day, and the result tells you when it has happened.

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