Days until calculator for countdowns and date counts

How to use the days until calculator

The page has one form with two date fields and a few settings.

1. Reference date starts on today's date, read from your device. Select Use today to reset it after typing something else, or type your own date as YYYY-MM-DD to use a date other than today.
2. Enter your Target date the same way, either a future date or a past one.
3. Under Show as, choose Days for a single number, or Weeks and days for the same total split into whole weeks and a remainder.
4. Check Count both dates to add one day and count the reference date and the target date together, instead of only the span between them.
5. Select Calculate. Read the result and the summary sentence, open View plain-text report for the full report, then select Copy result or Download report.

Reset clears both dates and restores today as the reference date.

How the count works

The calculator subtracts the reference date from the target date in whole calendar days. When the target is later, the result reads as days until. When it is earlier, the result reads as days since. The count never has a minus sign. The same date reads as Today, or as Same date when the reference date is not today.

By default the earlier date is excluded and the later date is included, so tomorrow is 1 day away and the same date is 0 days. Checking Count both dates adds one day and counts the reference and target dates once each, so the same date then reads as 1 day.

Choosing Weeks and days does not change the total day count. It only changes how the result is written, splitting the same number of days into whole weeks plus a remainder of 0 to 6 days.

Worked example

With 2026-09-22 as the reference date and 2026-12-25 as the target date, Days gives "94 days until", counting from Tuesday, September 22, 2026 to Friday, December 25, 2026, with neither date counted twice.

Switching to Weeks and days for the same two dates gives "13 weeks, 3 days until", with the report also stating the same total of 94 days, since the unit only changes the wording.

Checking Count both dates for the same pair adds the reference date itself to the total, giving "95 days until" instead of 94.

With the same reference date, a target of 2025-12-25 gives "271 days since", and the report's signed calendar days line reads -271.

The same reference date also accepts a far future target entered in extended-year notation: a target of +010000-01-01 gives "2,912,179 days until", counting all the way to January 1, in the year 10000.

Limits

This calculator counts every calendar day, including weekends and public holidays. A date typed in the wrong format, or an impossible date such as February 30, is rejected with an error rather than guessed at.

It has no time-of-day field. Whole calendar dates are compared using the proleptic Gregorian calendar for every year, so daylight-saving clock changes never add or remove a day from the result; this is not an elapsed-hours countdown.

The supported date range is -271821-04-20 to +275760-09-13, the full range the browser's native date type can represent, including years before year 1 and years beyond 9999, entered with a leading sign and six digits, for example +010000-01-01. A reference date or a target date outside that range gives an error that states the supported range.

Dates recorded in the Julian calendar, mostly dates before 1582, are not converted; the calculator applies today's Gregorian calendar backward to every year.