Pick a date and time.

A countdown to any date and time

The how-long-until tool takes any future date and time and produces a live countdown with the same flip-clock as the named countdowns. Pick a date in the input above and the clock starts immediately. The URL updates as you type so you can share the page with the target encoded in the query string.

Anyone who opens the shared URL sees the same target date, computed in their own local timezone. That makes the page useful for coordinating across timezones without explicit timezone conversion.

When to use this instead of a named countdown

The named pages (Friday, midnight, and so on) are the right tool for recurring weekly or daily targets. You bookmark them once and the countdown is always correct.

This tool is the right one for one-off targets: a wedding date, a flight, a release date, a contract deadline, an exam, a launch. The target is anchored to a specific moment on the calendar, not a recurring weekday or boundary.

How the count is calculated

Your browser parses the date you enter as a local-time moment, which means a target of "2026-08-15 14:00" is 2 PM local on August 15. We subtract the current local time from the target time and split the difference into days, hours, minutes and seconds. The seconds tick once a second using setInterval(tick, 1000), the same shared cadence the named countdowns use.

Daylight-saving transitions in the gap between now and the target are handled automatically by the browser's Date arithmetic. The displayed countdown therefore stays accurate even if a DST shift falls inside the interval.

Sharing a countdown

Once you've entered a target, the URL bar contains the date as a query parameter (?target=…). Copy that URL and anyone who opens it sees the same countdown in their own timezone. The target encoding uses ISO-8601 local time, so the same characters mean the same wall-clock moment for every viewer.

If your target is anchored to a specific timezone, like a 4 PM Pacific launch from London, the simplest approach is to encode the moment in your audience's timezone and tell them so explicitly. The page itself doesn't perform timezone conversion at the URL level.

Things people use this for

Common targets we see in shared URLs: weddings, exam dates, project deadlines, lease end dates, vacation start dates, product launches, retirement dates, baby due dates, payment-clearance dates. Each one is anchored to a specific Gregorian moment, which is the right shape for this tool.

For recurring weekly events, point people at one of our named weekday pages. For age-specific milestones like "I'll be 30 in X days", the age calculator handles the calendar arithmetic and surfaces the next-birthday weekday.

A note on accuracy across long intervals

For short targets (anything inside a year), the countdown is straightforward: subtract now from the target and split the millisecond difference into days, hours, minutes and seconds. For longer targets, the same arithmetic still works, but the days field grows beyond two digits. The flip cards on the page widen automatically so a four-digit day count (10,000+ days, around 27 years) still renders cleanly.

Daylight-saving transitions in the interval are handled correctly because the browser's Date arithmetic already accounts for them. A target of "3 PM on the second Sunday of November" reads as 3 PM local on both sides of the autumn DST change.

Limits of the tool

Targets in the past show a frozen countdown at zero rather than a negative number. Targets further than 100 years out work but stretch the days-display: the flip cards widen to accommodate four-digit day counts. Targets across calendar reforms (before October 15, 1582 on the Gregorian calendar) use proleptic Gregorian arithmetic, which is the standard convention for software but isn't historically faithful.

A few example targets

Some sample dates people commonly enter, by way of giving you a sense of the tool's range. Wedding anniversary on the 14th of next August: pick the date, the page produces a live countdown you can revisit each month. Project deadline on the 31st of the current quarter: pick the date and time, share the URL with your team, everyone sees the same target. Flight departure at 9:25 PM next Saturday: pick the date and exact time, the live count drops to the second. Lease end: enter the calendar date, watch the days tick down at a glance whenever you reload the page.

For recurring weekly targets, the named countdown pages are the right place. The hub lists every named countdown the site supports.

A note on calendar systems

The tool uses the Gregorian calendar exclusively, which is the civil calendar used by most of the world. Lunar calendars (Chinese, Hebrew, Islamic), Hindu calendars, and other alternative reckonings are not supported directly. If you need to count down to a date in another calendar, look up its Gregorian equivalent first and enter that.

For movable Christian feasts, our Easter page handles the computus. Other movable holidays (Mardi Gras, Pentecost, Trinity Sunday, Corpus Christi) can be derived from Easter by adding or subtracting the known offset.