Date Calculator

To find what date is 30 days from today, set Start Date to today, leave direction as "Add," enter 30 in the Days field, and click Calculate. The result depends on the current date — if today is May 15, 2026, then 30 days later is June 14, 2026. The calculator accounts for the varying number of days in each month and leap years automatically. Use the "Today" quick button to set the start date without typing.

Enter your start date, select "Add," then enter the number of months in the Months field. Adding months is not the same as adding 30 days per month — this calculator adds true calendar months. For example, adding 1 month to January 31 gives February 28 (or 29 in a leap year), because February has fewer days. Similarly, adding 1 month to March 31 gives April 30. This is the correct behavior for contract deadlines, subscription renewals, and billing cycles.

Calendar days include every day of the week, including Saturdays and Sundays. Business days count only Monday through Friday. If you select "Business days only," the calculator skips weekends when counting. Example: adding 10 business days to a Monday gives the Monday two weeks later (skipping 4 weekend days). This is useful for calculating shipping deadlines, legal notice periods, payment terms, and HR processes where weekends are excluded. Note that public holidays are not excluded — adjust manually for those.

Set Start Date to today, change direction to "Subtract," enter 90 in the Days field, and click Calculate. The result is the date 90 days before today. This is useful for calculating lookback periods, financial reporting windows, statute of limitations checks, and return or refund windows. You can also combine units — for example, subtract 3 months instead of 90 days to get the same month three calendar months back (which differs slightly due to month lengths).

When you add years to a date, the calculator adds true calendar years. If the original date is February 29 (a leap day) and you add 1 year to reach a non-leap year, the result becomes February 28. Adding 4 years from February 29 returns to February 29, since most 4-year gaps include a leap year. February 29, 2000 + 1 year = February 28, 2001. February 29, 2000 + 4 years = February 29, 2004 (if 2004 is a leap year, which it is). Edge cases like these are handled correctly by this calculator.

A fiscal year (FY) is a 12-month accounting period that may or may not align with the calendar year. US federal government: October 1 to September 30. UK government: April 6 to April 5. Many corporations use their own FY start. To find the end of a fiscal year, enter the FY start date and add exactly 1 year, then subtract 1 day. Example: FY starting April 6, 2025 ends April 5, 2026. To find what quarter a date falls in, calculate the number of months since the FY start and divide by 3.

Enter the date the contract starts or notice is given as Start Date. Add the required period (e.g., 30 days, 3 months, 1 year). For legal deadlines, always clarify whether the period is in calendar days, business days, or calendar months — the result differs. Example: a 30-day notice starting February 1 ends March 3 (calendar days) or March 17 (business days, skipping weekends). For critical legal matters, verify with a solicitor or attorney, as some jurisdictions exclude the first day, last day, or both from the count.

Switch to the "Date Difference" tab, set Start Date to today, and set End Date to December 25 (Christmas) or December 31 (New Year's Eve). The result shows the exact number of days, and dividing by 7 gives the weeks. For even easier use, click "Today" for the start date and "Dec 31" for the end date to get the days remaining in the current year in one click. This works for any recurring annual date — just enter the upcoming date as the End Date.

ISO 8601 is the international standard for dates and times, using the format YYYY-MM-DD (year-month-day). Example: May 15, 2026 = 2026-05-15. This format is unambiguous across cultures — unlike 05/06/2026 which means June 5 in the US but May 6 in Europe. ISO 8601 sorts chronologically when sorted alphabetically, making it ideal for filenames and databases. The HTML date input in this calculator uses ISO 8601 format internally. Times extend to YYYY-MM-DDTHH:MM:SS, and durations use P1Y2M3D (1 year, 2 months, 3 days).

Use the Date Difference tab: enter the birth date as Start Date and today as End Date. The result shows the total days, weeks, and months. Divide total days by 365.25 for age in decimal years, or use the Months figure divided by 12. For a dedicated age calculator with years, months, and days clearly broken out, visit our Age Calculator page. To find the exact date when someone turns a specific age, use the Add/Subtract tab: enter the birth date and add the number of years of the desired age.