Days Until & Date Calculator — Countdown, Days From, Months From
How many days until an exam, a trip or a cancellation deadline — and what date is 100 days from now?
How it works
- Days until — counts the days from midnight on the start date to midnight on the target date. A future date shows D-number, today shows D-DAY and a past date shows D+number. Leave the start date blank to count from today.
- Days from a date — the start date plus that many days, added on the calendar, so month ends and leap years take care of themselves.
- Months from a date — moves the month and keeps the day of the month. If the new month has no such day, it uses that month's last day. One month after January 31 is February 28 (29 in a leap year), not March 3.
Countdown examples
| Case | Start date | Target date | Result |
|---|---|---|---|
| New Year's Day to Christmas | Thu, Jan 1, 2026 | Fri, Dec 25, 2026 | D-358 |
| One year across a leap day | Mon, Mar 1, 2027 | Wed, Mar 1, 2028 | D-366 |
| A date that has already passed | Mon, Oct 19, 2026 | Thu, Oct 1, 2026 | D+18 |
Days and months from a date
| Case | Start date | Offset | Date |
|---|---|---|---|
| Jan 31 + 1 month | Sat, Jan 31, 2026 | 1 month later | Sat, Feb 28, 2026 |
| Jan 31 + 30 days | Sat, Jan 31, 2026 | 30 days later | Mon, Mar 2, 2026 |
| Mar 31 + 1 month | Tue, Mar 31, 2026 | 1 month later | Thu, Apr 30, 2026 |
| Jan 31 in a leap year + 1 month | Mon, Jan 31, 2028 | 1 month later | Tue, Feb 29, 2028 |
| Oct 1 + 100 days | Thu, Oct 1, 2026 | 100 days later | Sat, Jan 9, 2027 |
"1 month later" and "30 days later" can be different dates. Use months when the rule is "the same day every month" — a subscription renewal or the end of a contract — and days when the rule is "within N days". The dates in the tables come from the same function as the calculator on this page.
When to use it
- Counting the days to an exam, a trip or an anniversary
- Working out the day a free trial ends or points expire — set your cancellation deadline a day or two before the billing date to avoid an unwanted charge
- Picking a target date such as "100 days from today"
Dates are counted on this device's calendar (local midnight). Only midnights are compared, so a day is always counted as exactly one day, even in regions with daylight saving time.
Frequently asked questions
Is the start date itself counted as day 1?
No. It counts the difference between the start date and the target date, so tomorrow is D-1 when you count from today. For an anniversary that counts the first day as day 1 ("100 days together"), subtract one day from the result.
Why is one month after January 31 February 28?
February has no 31st, so the date is set to the last day of that month. Rolling over into March would break "same day every month" calculations such as billing dates.
How far ahead can it calculate?
Up to 3,650 days (10 years) or 120 months.
Are the dates I enter saved?
No. The calculation happens only in your browser; nothing is sent to a server or stored.
More free tools
Add it to your home screen and it opens like an app — after the first visit it works offline too. What you type never leaves your device.