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How to use the date calculator
This date calculator does three jobs: it counts the days between two dates, it finds the date a set number of days, weeks or months before or after another, and it counts down to a date you care about. Pick the tab that matches your question. Everything recalculates as you type, and every date shows its weekday and ISO week number underneath.
- Between dates gives the gap in years, months and days, plus total days, weeks, hours, minutes and business days.
- Add / subtract moves a date forward or back by calendar time or by business days.
- Countdown shows how many days are left until a date, with a live clock when you count from today.
Open Workdays and holidays to change which days count as the weekend and to list holidays to skip. These settings apply to all three tabs.
How many days are there between two dates?
Subtract the earlier date from the later one. January 1, 2026 to December 25, 2026 is 358 days. The calculator converts both dates to day numbers and takes the difference, so leap years and month lengths are handled for you.
Inclusive days = end date − start date + 1
The one decision you have to make is whether the last day counts. A hotel stay from the 1st to the 3rd is 2 nights, so leave the switch off. Vacation days from Monday the 1st to Wednesday the 3rd are 3 days off work, so switch Include the end date on. Most "days between dates" questions online mean the first version, which is why it is the default.
Years, months and days
The years-months-days answer counts like a calendar. From March 15 to October 11 is 6 months and 26 days: six full months gets you to September 15, then 26 more days.
What date is 30, 60 or 90 days from today?
Use the Add / subtract tab and tap one of the quick buttons. Deadlines written in days often land on a weekend, so check the weekday. This table starts from Sunday, October 11, 2026:
| Added | Date after | Date before |
|---|---|---|
| 30 days | Tue, Nov 10, 2026 | Fri, Sep 11, 2026 |
| 45 days | Wed, Nov 25, 2026 | Thu, Aug 27, 2026 |
| 60 days | Thu, Dec 10, 2026 | Wed, Aug 12, 2026 |
| 90 days | Sat, Jan 9, 2027 | Mon, Jul 13, 2026 |
| 180 days | Fri, Apr 9, 2027 | Tue, Apr 14, 2026 |
| 365 days | Mon, Oct 11, 2027 | Sat, Oct 11, 2025 |
"90 days" and "3 months" are not the same thing. Three months from October 11 is January 11, two days later than 90 days. If a contract says months, add months; if it says days, add days.
What happens with January 31 plus one month?
You get February 28 (or February 29 in a leap year such as 2028). February has no 31st, so the date moves to the last day of the month. Excel's EDATE function and most banking systems do the same. The calculator shows a warning whenever this happens, because it means adding one month and then subtracting one month will not bring you back to the 31st.
| Start | + 1 month | + 3 months |
|---|---|---|
| Jan 31, 2026 | Feb 28, 2026 | Apr 30, 2026 |
| Jan 31, 2028 | Feb 29, 2028 | Apr 30, 2028 |
| Mar 31, 2026 | Apr 30, 2026 | Jun 30, 2026 |
| Aug 31, 2026 | Sep 30, 2026 | Nov 30, 2026 |
How do I count business days between two dates?
Count the days that are neither weekend days nor holidays. January 1 to December 25, 2026 contains 256 weekdays from Monday to Friday. That figure still includes Thanksgiving, July 4th and the other federal holidays, so for a real deadline paste your company's holiday list into the holidays box, one date per line. Each one that falls on a weekday is taken off the count, and the month-by-month table shows where they landed.
Two things trip people up. First, a holiday on a Saturday is not subtracted twice; it was already a weekend day. If your employer gives the Friday off instead, add that Friday. Second, the weekend is not Saturday and Sunday everywhere. Tap Fri and Sat for countries with a Friday-Saturday weekend, or leave only Sunday for a six-day week.
Adding business days
"Ships within 10 business days" counted from Friday, October 16, 2026 means Friday, October 30. The start day is not counted, matching how shipping and legal deadlines are usually read. If the rule you follow counts the start day, subtract one.
How many days until Christmas?
From October 11, 2026, Christmas Day is 75 days away and New Year's Day 2027 is 82 days away. The Countdown tab has quick picks for New Year, Valentine's Day, July 4th, Halloween, US Thanksgiving (the fourth Thursday of November, worked out for each year), Christmas and New Year's Eve.
Week numbers and the year-end trap
Week numbers follow ISO 8601: weeks start on Monday and week 1 is the week containing the year's first Thursday. The trap is at the edges of the year. January 1, 2027 is a Friday, so it belongs to week 53 of 2026, not week 1 of 2027. If you plan in week numbers, check the year shown next to the week.
A limitation worth knowing: everything here counts whole calendar days. Hours and minutes are days × 24 and × 1,440, so a span that crosses a daylight saving change is off by an hour in real clock time. For times of day across zones, the time zone converter is the better tool.
Frequently asked questions
How many days are there between two dates?
Subtract the earlier date from the later one in whole days. From January 1 to December 25, 2026 is 358 days, or 359 if you count both the first and the last day. The calculator shows both with the include-end-date switch.
What date is 90 days from today?
Add 90 calendar days to today's date. From October 11, 2026, 90 days later is Saturday, January 9, 2027. Use the Add / subtract tab and press the 90 days button for any other start date.
How do I count business days between two dates?
Count the days that are not weekend days and not public holidays. January 1 to December 25, 2026 holds 256 weekdays (Monday to Friday), before any holidays are removed. Add your holiday dates under Workdays and holidays to subtract them.
What is January 31 plus one month?
February 28, or February 29 in a leap year. February has no 31st, so the calculator moves to the last day of the month, the same rule spreadsheets use with EDATE. It tells you when this happens.
Does the calculator count the start date and the end date?
By default it counts the start date but not the end date, so Monday to Friday is 4 days. Switch on Include the end date to get 5, which is how leave days and daily rentals are usually counted.
How many days until Christmas?
From October 11, 2026 there are 75 days until December 25, 2026. Open the Countdown tab and tap Christmas, and it counts from today with a live clock to midnight.
What week number is a date?
The calculator shows the ISO 8601 week, where weeks start on Monday and week 1 contains the first Thursday of the year. December 25, 2026 is in week 52, and January 1, 2027 still belongs to week 53 of 2026.