Date Calculator

Date calculator at a glance#

A date calculator finds the number of days between two dates, or shifts a date forward or back by a set number of days. To count the days between, subtract the start date from the end date. To shift a date, add or subtract the day count from the start date and carry over month and year boundaries.

Worked example: from January 1 to March 1, 2025 is 59 days. January has 31 days and February has 28 in 2025, so 31 plus 28 is 59. Adding 90 days to January 1, 2025 lands on April 1, 2025.

The two 2025-to-2024 rows differ by one day because 2024 is a leap year, so February has 29 days instead of 28. A date calculator counts that extra day for you. Counting can be exclusive or inclusive: exclusive counting gives the gap between the dates (59 days from Jan 1 to Mar 1, 2025), while inclusive counting includes both the start and end day and gives one more (60 days). Use exclusive for a duration and inclusive when both days count, such as a hotel stay or an event that runs through its last day.

Enter your two dates, or a start date and a day count, in the calculator above for the exact result. It accounts for leap years and varying month lengths, so the figure is correct without manual carrying.

What a date calculator does#

A date calculator answers two kinds of question: how many days lie between two dates, and what date falls a set number of days before or after a given date. It counts varying month lengths and leap years for you, which is where hand counting usually goes wrong.

Some versions count calendar days, where every day counts, and others count business days, where weekends and chosen public holidays are skipped. Pick the mode that matches your task: calendar days for a countdown, business days for a work deadline.

Calendar days vs business days#

Calendar days include weekends. Business days count only Monday to Friday and can also drop holidays you select. A 30 calendar day window is roughly 21 to 22 business days once two weekends are removed, so a deadline quoted in working days lands later on the calendar than the same number of calendar days.

Common uses#

• Counting down to a holiday, birthday or trip.
• Finding a deadline by adding days to a start date.
• Working out how long ago a past date was.
• Checking a visa, warranty or notice period end date.

Inclusive vs exclusive counting#

Exclusive counting gives the gap between two dates and is what you want for a duration. Inclusive counting also counts the start and end day, giving one more. From June 1 to June 5 is 4 days exclusive but 5 days inclusive. Use inclusive when both ends count, such as a hotel stay billed through its last night or an event that runs through its final day.

Frequently asked questions#

What is a date calculator and what can it tell me?#

It finds the number of days between two dates, or shifts a date by a number of days, weeks or months. Use it to plan events, track deadlines, or count down to a holiday.

Does it account for leap years?#

Yes. Every February 29 inside the range is counted. January 1 to March 1 is 59 days in 2025 but 60 days in 2024, because 2024 is a leap year and February has an extra day.

Can it add or subtract days from a date?#

Yes. Enter a start date and a number of days, weeks or months to add or subtract, and it returns the resulting date, carrying over month and year boundaries. Adding 90 days to January 1, 2025 lands on April 1, 2025.

How does it handle business days and holidays?#

In business day mode it skips Saturdays and Sundays, and skips any public holidays you select for your country or region, so the count reflects actual working days.