Days Between Dates & Countdown Calculator
Find the number of days between two dates, count down to a deadline or holiday, and add or subtract days from any date. Results also show weeks, months and day-count milestones.
Pick a start date and a target date, then press Calculate.
Milestones from the start date (start date = day 1)
| Milestone | Date | From today |
|---|
How the day count works
The main result is the plain difference target date − start date. Tomorrow is 1 day away, and the same date is 0 days. This is the number you want for countdowns (“how many days until my vacation?”) and for “how many days ago”.
| Start date | Target date | Result |
|---|---|---|
| October 19, 2026 | December 25, 2026 | 67 days until Christmas |
| October 19, 2026 | January 1, 2027 | 74 days until New Year’s Day |
| October 19, 2026 | October 19, 2026 | 0 days (same day) |
| October 19, 2026 | October 9, 2026 | 10 days ago |
The calculator also breaks the gap into weeks and days, and into calendar months and days. A month is counted when the same day of the month comes around again (January 31 to February 28 counts as one month, because February has no 31st).
Inclusive vs. exclusive counting
There are two ways to count days, and they differ by exactly one:
- Exclusive (the default): count the nights in between, or “end − start”. A hotel stay from Monday to Friday is 4 nights. Most countdowns, deadlines (“within 30 days”) and date-difference functions in spreadsheets work this way.
- Inclusive: count both the first and the last day. A conference running Monday through Friday is 5 days. Use this for “day 1 of my challenge”, sobriety or streak counters, school-day counts and leave requests that include both ends.
The Inclusive box in the result shows the exclusive difference + 1. In the add-days tool, turn on Count the start date as day 1 to get the date of “day N” (start + N − 1); leave it off for “N days after” (start + N). For example, 90 days after October 19, 2026 is January 17, 2027, while day 90 counting October 19 as day 1 is January 16, 2027.
Milestones
The milestone table lists day 100, 200 … 1,000, then every 500 days up to 3,000, plus yearly anniversaries, counting the start date as day 1. That makes it handy for tracking a habit streak, the age of a baby or a project in days, or how long you have been together with someone. Yearly anniversaries fall on the same calendar date; for a February 29 start date, non-leap years use February 28.
Frequently asked questions
Does the calculator handle leap years?
Yes. All results use the real Gregorian calendar, including February 29 in leap years. For example, February 28 to March 1, 2028 is 2 days.
How do I count business days only?
This tool counts calendar days. As a quick estimate, the weeks figure tells you how many full weekends fall in the range (5 working days per full week), but public holidays differ by country and state, so check your local calendar for an exact working-day count.
Which time zone is “today”?
Your device’s date. If you leave the start date blank, today’s date from your browser is used, and the “From today” column in the milestone table is also based on your local date. Only dates matter here, so daylight saving time changes do not affect the result.
What does D-100 mean?
It is a common shorthand for “100 days to go”. D-day is the event day itself, and D+10 means 10 days after it. You will see the shorthand next to the result. Want to count characters in an announcement instead? Try the character counter.