Date Calculator: Days Between Dates, Add or Subtract Days
Count the days between two dates, find the date N days or months before or after, and count business days that skip weekends and U.S. federal holidays.
Including or excluding the start date can change the answer by one day.
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To find an earlier date, choose ‘Subtract (-)’ above. The number must be 0 or more.
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How to use
How this date calculator works
This date calculator handles the three questions people ask most about dates. Days between dates counts how many days, weeks, months and years lie between a start and an end date. Add or subtract finds the date that falls a number of days, weeks, months or years before or after a starting date. Business days counts weekdays in a range, or finds the date that is a given number of business days away, skipping weekends and U.S. federal holidays. Pick a mode, enter your dates, and the answer appears below instantly. Everything is calculated in your browser, and no dates are stored or sent anywhere.
Counting the days between two dates
The tool subtracts the start date from the end date using whole calendar days, so daylight saving time never throws the count off by an hour. By default the start date is not counted. From January 1 to January 2 is one day. If you tick Include start date, both ends count, which turns the same example into two days. The right choice depends on the situation: a hotel stay from the 1st to the 5th is four nights, but a conference that runs on the 1st through the 5th is five days. The results also show the span as weeks and days, and as an approximate number of years, months and days. For example, January 1, 2026 to December 31, 2026 is 364 days, or 52 weeks and 0 days, and 365 days if you include the start date.
Adding and subtracting dates
Enter a starting date, choose Add or Subtract, type a number and pick a unit. Days and weeks are exact: 90 days after January 15, 2026 is April 15, 2026. Months and years follow the calendar. Adding one month to January 31 gives “February 31,” which does not exist, so the calculator rolls forward and shows March 3, 2026. Adding one year to February 29, 2028 lands on March 1, 2029 for the same reason. If a contract says “one month from signing,” check how it handles month-end dates, because some documents use the last day of the following month instead.
Business days and U.S. federal holidays
A business day here is a weekday that is not a U.S. federal holiday. The calculator uses the eleven federal holidays: New Year’s Day, Martin Luther King Jr. Day, Presidents’ Day, Memorial Day, Juneteenth, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving and Christmas Day. When a holiday falls on a Saturday it is observed on the Friday before, and when it falls on a Sunday it is observed on the Monday after. For example, July 4, 2026 is a Saturday, so the day off is Friday, July 3. Ten business days after Friday, June 26, 2026 is Monday, July 13, 2026, because the count skips the weekends and July 3. The chips under the result show which holidays were skipped. Holiday data is built in for 2024 through 2027, and for other years the tool excludes weekends only and tells you so.
When “business day” means something different
Banks and the Federal Reserve follow the federal holiday calendar, so wires and ACH transfers usually settle on the business days shown here. The stock market has its own schedule: it closes on Good Friday, which is not a federal holiday, and it is open on some bank holidays only partially or not at all. Courts, state agencies, schools and private employers often add or remove days, such as Cesar Chavez Day or the day after Thanksgiving. Shipping companies may count Saturdays as delivery days. Treat the result as a solid estimate and confirm deadlines against the rules that apply to you.
Common uses
- Notice periods and deadlines. Count 30 days from a notice date, or find the last day to respond. Legal and tax deadlines have their own rules for weekends and holidays, so check them.
- Projects and delivery. Find a due date that is 15 business days after an order, or the number of working days left before a launch.
- Lease and subscription dates. See when a 90-day trial or a 12-month lease ends.
- Travel and events. Count nights between check-in and check-out, or the days remaining until a trip.
- Personal milestones. Work out how many days you have been in a job or how long until an anniversary.
Leap years in one minute
A year is a leap year when it is divisible by 4, except century years, which must be divisible by 400. That is why 2024 and 2028 have a February 29, while 1900 did not and 2000 did. The calculator uses the built-in calendar, so leap days are counted automatically in every range.
Quick reference: how long is…
A week is 7 days, a common year is 365 days (52 weeks and 1 day) and a leap year is 366 days. The months have 28 to 31 days, so “30 days” and “one month” are not the same thing: 30 days after January 31 is March 2 in a common year, while one month after January 31 is March 3 here because February runs short. A quarter is about 91 days. When you need to be exact, use days; when a document says months or years, use the month and year options.
Frequently asked questions
How do I calculate the number of days between two dates?
Pick “Days between dates,” enter the start and end dates and press Calculate. The tool subtracts the dates in whole days. Tick “Include start date” if you want both the first and the last day to count.
How do I find the date 90 days from today?
Use the Add or subtract tab. The base date is filled with today’s date automatically. Keep Add selected, type 90, choose Days and press Calculate. The result shows the full date with the day of the week.
What happens if I add a month to the 31st?
When the target month is shorter, the extra days roll into the next month. January 31 plus one month becomes March 3 in 2026 because February has 28 days. If you need the last day of the month instead, subtract a day from the first day of the following month.
Which days does the business day calculator skip?
Saturdays, Sundays and the observed U.S. federal holidays for 2024 through 2027. Outside those years it skips weekends only and shows a note. Your employer, bank or court may observe a different list.
Does the count include the start date for business days?
No. The count begins with the day after the start date, which matches how most deadlines read, for example “within 5 business days of receipt.” If the start date itself counts, subtract one day from your start date first.
Can I use this for legal or contract deadlines?
It is a convenient check, but legal deadlines can depend on court rules, time zones, service methods and local holidays. Confirm important dates with the governing rules or a professional.
Is my data saved anywhere?
No. The tool runs in your browser, and the dates you enter are not stored or transmitted.