Days Until / Since Calculator

How it works

This is the simplest date utility on the site: enter a future date and see how many days until it; enter a past date and see how many days since. Useful for counting down to vacations, birthdays, deadlines, retirement, weddings, or counting up since events you want to track.

The calculator subtracts the target date from today's date at the day boundary (midnight local time). If the target is today, the result is 0. If tomorrow, 1 day until. If yesterday, 1 day since. The label switches automatically based on direction.

Other useful unit views: weeks (days ÷ 7) and hours (days × 24). For very long countdowns, the day count grows large fast — a year is about 365 days, so a 10-year anniversary is around 3,650 days.

Embedding tip: bookmark this page with a query string and the target date pre-filled, and you have a permanent countdown link. (Currently the date is in component state only; converting to a URL parameter is a small enhancement if you want bookmarkable countdowns.)

For events that recur annually (birthdays, anniversaries), this calculator gives the days until the next occurrence if you enter the current year's date — which means after the date passes, you may want to update to next year's date manually.

Time-zone caveat. The calculator uses the browser's local time zone. If you're in California planning around a New York event, "today" and "tomorrow" are defined by your local clock. For zone-sensitive countdowns (a launch at midnight EST), use the time-zone converter alongside this calculator.