How to use this calculator
Pick what you want to do at the top.
Days between dates
- Enter a start date (today by default) and an end date.
- Choose whether to include the end date.
- Choose All days or Business days only. For business days you can also skip US federal holidays.
You get the number of days, the same span in weeks and days and in months and days, the number of business days, and a list of any holidays that were skipped.
Add or subtract
- Enter a start date.
- Choose Add or Subtract, an amount and a unit: days, weeks, months, years or business days.
You get the resulting date, the day of the week it falls on, and how many calendar days apart the two dates are.
How the days are counted
Every date is turned into a day number (days since January 1, 1970), and the difference is a plain subtraction:
Because dates are whole calendar days, daylight saving time can’t add or remove an hour. March 7 to March 9, 2026 is 2 days even though the clocks spring forward on March 8.
Example: from Friday, November 6, 2026 to Friday, December 31, 2027 is 420 days, which is exactly 60 weeks, or 13 months and 25 days. Of those days, 120 fall on weekends, leaving 300 business days. Take out the 14 federal holidays that fall on weekdays in that span and it’s 286.
Weeks are the days divided by 7, with the leftover days shown. Months and days count whole calendar months from the start date first, then the days left over, the same way an age calculator counts age.
Business days and federal holidays
A business day here is any Monday to Friday. If you also skip federal holidays, the calculator uses the dates federal offices are actually closed. Under federal law, a holiday that falls on a Saturday is observed the Friday before, and one that falls on a Sunday is observed the Monday after. That’s why Independence Day 2026 is observed on Friday, July 3, and New Year’s Day 2028 is observed on Friday, December 31, 2027.
| Holiday | 2026 (observed) | 2027 (observed) |
|---|---|---|
| New Year’s Day | Thu, Jan 1 | Fri, Jan 1 |
| Martin Luther King Jr.’s Birthday | Mon, Jan 19 | Mon, Jan 18 |
| Washington’s Birthday | Mon, Feb 16 | Mon, Feb 15 |
| Memorial Day | Mon, May 25 | Mon, May 31 |
| Juneteenth | Fri, Jun 19 | Fri, Jun 18 (for Sat, Jun 19) |
| Independence Day | Fri, Jul 3 (for Sat, Jul 4) | Mon, Jul 5 (for Sun, Jul 4) |
| Labor Day | Mon, Sep 7 | Mon, Sep 6 |
| Columbus Day | Mon, Oct 12 | Mon, Oct 11 |
| Veterans Day | Wed, Nov 11 | Thu, Nov 11 |
| Thanksgiving Day | Thu, Nov 26 | Thu, Nov 25 |
| Christmas Day | Fri, Dec 25 | Fri, Dec 24 (for Sat, Dec 25) |
These match the schedule published by the U.S. Office of Personnel Management. Inauguration Day, a holiday only for federal employees in the Washington, DC area every four years, isn’t included. Banks, the stock market and private employers set their own holiday calendars, so check yours if a deadline depends on them.
With holidays skipped, 2026 has 250 business days and 2027 has 249. Business days in each month of 2027:
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 19 | 19 | 23 | 22 | 20 | 21 | 21 | 22 | 21 | 20 | 20 | 21 |
Adding and subtracting
- Days and weeks move along the calendar exactly: 90 days after November 6, 2026 is Thursday, February 4, 2027.
- Months and years keep the same day of the month: 6 months after November 6, 2026 is Thursday, May 6, 2027. If that day doesn’t exist (January 31 plus one month), you get the last day of the month instead.
- Business days step one weekday at a time and don’t count the start date. Ten business days after Friday, December 18, 2026 is Friday, January 1, 2027 counting weekends only, but Tuesday, January 5, 2027 once Christmas and New Year’s Day are skipped.
Tips for common deadlines
- “Within 30 days” usually means calendar days. Unless the rule says otherwise, start counting the day after the event.
- Shipping and processing times are usually quoted in business days. Turn on holidays for anything that goes through a bank or a government office.
- Notice periods at work are often counted in weeks or calendar days. To total the hours you worked in a week, use the hours calculator, and see what a pay period is worth with the paycheck calculator.
- Pregnancy is counted in weeks from the first day of your last period. The due date calculator handles that for you.
Assumptions and limitations
- Dates use the Gregorian calendar and are accepted from the year 1000 to 9999.
- Federal holidays follow today’s rules for every year, except that Martin Luther King Jr. Day is counted from 1986 and Juneteenth from 2021, the first years each was observed. Before 1971 several holidays fell on fixed dates rather than Mondays, and Veterans Day was in October from 1971 through 1977, so business-day counts for those years are approximate.
- State holidays, religious holidays and company closures aren’t included.
- Legal deadlines can have special counting rules (for example, rolling forward when the last day is a weekend). When it matters, check the rule that applies.
Sources
Frequently asked questions
How many days are there between two dates?
Subtract the earlier date from the later one, counted in calendar days. By default the start date is counted and the end date is not, so Monday to Tuesday is 1 day. Turn on "Include the end date" if you need to count both days, as you would when counting the days of an event.
How do I count business days between two dates?
Choose "Business days only". The calculator counts Mondays through Fridays in the range and, if you choose, also skips US federal holidays on the dates they're observed. For example, there are 261 weekdays in 2026 and 250 once the 11 federal holidays are taken out.
Should I include the end date?
It depends on what you're counting. For "how many days until" or a length of time, leave it off. For counting days of an event, a trip or a leave period where both the first and last day count, include it; the answer goes up by one.
What is 90 days from today?
Set the mode to "Add or subtract", leave the start date as today and add 90 days. From Friday, November 6, 2026, 90 days later is Thursday, February 4, 2027. Deadlines stated in days usually mean calendar days, but check whether yours means business days.
What happens when I add a month to January 31?
There's no February 31, so the calculator uses the last day of February, February 28 or February 29 in a leap year. The same rule applies to years, so adding one year to February 29, 2024 gives February 28, 2025.
Which holidays count as federal holidays?
The 11 permanent holidays set by 5 U.S.C. 6103 include New Year's Day, Martin Luther King Jr.'s Birthday, Washington's Birthday, Memorial Day, Juneteenth, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving and Christmas. When one falls on a Saturday, federal offices close the Friday before; on a Sunday, the Monday after.
Updated November 2026. Results are estimates for educational purposes and depend on the inputs you provide.