Date Calculator

Fill in how far you want to move and the result updates straight away. Leave any field you do not need at zero.

1. Pick a Start date. It begins as today, so you can usually skip this step for a deadline counted from now.
2. Set the Operation to Add to the date or Subtract from the date. Every number below it is entered as a positive value, and the operation decides the direction.
3. Enter any combination of Years, Months, Weeks and Days. The Days field starts at 90, which suits a 90 day plan.
4. Tick Count the days as business days (Mon to Fri) if the Days figure should include only weekdays.
5. Read the resulting date and weekday at the top, then the calendar days and weeks between the two dates, how far the result is from today, and its day of the year.

When several units are filled in, the order matters, so the tool always follows the same one. Years and months are applied first, then weeks, then days. A year is treated as 12 months.

Take a start date of Wednesday, October 28, 2026 and the default 90 days. October has three days left, November has 30 and December has 31, which makes 64; another 26 days lands on Tuesday, January 26, 2027. The tool reports 90 calendar days, about 12.86 weeks, and the day of the year of the result.

Months are trickier because they differ in length. If the target month does not have the day you started on, the result is shortened to that month's last day, and the tool says so in its note:

Adding a month is not the same as adding 30 days. From January 31, 2026, 30 days later is March 2, while one month later is February 28. If a contract says "one month", check which reading it intends. For a count of days between two known dates the other way round, the date difference calculator is the quicker route.

You can combine units in one go. Starting on Wednesday, October 28, 2026, add 1 year, 2 months, 3 weeks and 4 days. The year and months come first and give December 28, 2027, three weeks later is January 18, 2028, and four more days is Saturday, January 22, 2028. Doing the same sum in a different order can give a different answer near the end of a month, which is why the order is fixed.

With the business day box ticked, the Days field counts only Monday to Friday and steps over Saturdays and Sundays. Ten business days after Wednesday, October 28, 2026 is Wednesday, November 11, 2026, which is 14 calendar days later because two weekends are skipped. Years, months and weeks are still added first as ordinary calendar units, and only the Days figure is counted by weekdays.

One important limit: public holidays are not skipped. November 11 is a federal holiday in the United States, so a real office might not count it as a working day. If your deadline depends on holidays, move the result forward by hand, or count the holidays and add them as extra business days.

People commonly use a date calculator for:

• Due dates, notice periods and 30, 60 or 90 day plans.
• Warranty, refund and return windows.
• Project deadlines, with weeks and days added separately.
• Course schedules and pregnancy milestones, though the pregnancy due date calculator is built for that purpose.

Other helpful tools are the age calculator for exact ages and the time calculator for lengths of time within a day. The result depends on your own calendar, with no time zone adjustment, and the dates you enter stay in your browser.