Date Difference Calculator

How the date difference is calculated

Enter any two dates and the calculator breaks the gap down three ways: an exact span in years, months, and days; the total number of days and weeks; and the number of business days (Monday–Friday) with weekend days and custom excluded weekdays shown separately. If the dates are in the wrong order it swaps them automatically.

Method

• Total days — the number of midnights between the two dates.
• Years / months / days — whole calendar years, then whole months, then leftover days, using real month lengths and leap years.
• Business days — every weekday in the range, minus any custom excluded weekdays you enter for holidays or closures.
• Include end date — adds one day, turning an exclusive count into an inclusive one.

Worked example

From January 1, 2026 to December 31, 2026: 364 total days (52 weeks), which is 11 months and 30 days exactly. Of those, 261 are weekdays and 103 fall on weekends before any custom exclusions. Ticking "include end date" makes it a full 365 days — one calendar year.

Common reasons to count between dates

• Deadlines and notice periods — days until a due date, or a 30/60/90-day notice window.
• Contracts and leases — the exact term length, or time remaining before renewal.
• Projects — working days available for a task, excluding weekends and holidays.
• Personal milestones — days since an anniversary, or a countdown to a trip or event.

Getting business days right

The weekday count already removes Saturdays and Sundays. Public holidays differ by country and region, so no universal list applies — subtract known holidays in your range yourself for a true working-day figure. The custom excluded weekdays option removes a whole day of the week (handy if your schedule also skips, say, every Friday). Decide too whether the count should include the end date — a contract "through December 31" is inclusive, while "days until December 31" usually is not.

Counting from a birth date? The age calculator adds a next-birthday countdown. For hours within a single day, use the time duration calculator.

Days between two dates: inclusive or exclusive?

Most elapsed-time calculations exclude the end date. January 1 to January 2 is one elapsed day because only one midnight separates the dates. An inclusive date count includes both calendar dates, making the same range two days. Inclusive counting is common for event days, accommodation days, and schedules that say “through” a final date. Exclusive counting is common for countdowns and nights between check-in and check-out.

Weeks and months between dates

Total weeks is total days divided by seven, so 45 days is about 6.43 weeks. Months are less uniform: a calendar month can contain 28, 29, 30, or 31 days. The exact result therefore counts whole calendar years and months before leftover days, while the approximate-months result uses the average Gregorian month length of 30.4375 days. Use the exact calendar span for anniversaries or contract terms and the decimal estimate for rough comparisons.

Business days between dates

A business day calculator normally counts Monday through Friday and excludes Saturday and Sunday. The result is useful for project schedules, invoice payment terms, shipping estimates, payroll periods, and service-level deadlines. Public holidays are not universal: a federal holiday in one country may be a working day elsewhere, and regional or company closures vary. Enter the number of known weekday holidays as custom exclusions to move from a weekday count toward a practical working-day count.

Leap years and different month lengths

The calculation uses actual calendar dates, so February 29 is counted in a leap year and short months are not treated as 30-day blocks. Gregorian leap years are generally divisible by four, except century years must also be divisible by 400. That makes 2024 a leap year, 2100 a common year, and 2000 a leap year. This matters when a date range crosses February or spans several years.

Common date duration searches

• How many days until a date: use today as the start and the future date as the end.
• How many days since a date: enter the past date first and today second.
• Working days in a project: use business days and subtract weekday holidays.
• Exact months between dates: read the years-months-days result rather than dividing by 30.
• Calendar days for a notice period: confirm whether the governing rule counts the first or final day.

Legal, payroll, and deadline caution

Holidays that move every year

Some dates are fixed and some are rules. Fixed dates never change; rule-based dates land on a different day each year, which is why a countdown has to compute them rather than store them.

Easter is the awkward one. It is a lunisolar date, so it can fall anywhere between 22 March and 25 April, and it is worked out with the Anonymous Gregorian algorithm rather than looked up. This calculator computes it for whatever year you are in, so the answer stays right in 2027 and beyond.

Courts, contracts, employers, and government agencies may use special counting rules for filing dates, holidays, weekends, time zones, and partial days. This calculator provides general calendar math and does not determine a legally binding deadline. When a missed date has financial or legal consequences, confirm the result with the applicable rule or a qualified professional.