# Days until January 21

Counts the days from today, or any date you choose, to the next January 21, with its day of the week.

- Page: https://www.acalculator.org/days/days-until-january-21
- JSON spec: https://www.acalculator.org/days/days-until-january-21.json
- Version: f847fb1bd7b0

## Default answer

Example with the default inputs (Count from September 30, 2026) on the example date Wednesday, September 30, 2026: From September 30, 2026, there are 113 days until January 21 on Thursday, January 21, 2027.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| from | Count from | The date to count from. Today, unless you change it. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| days | Days until January 21 | Whole days from the start date to the next January 21; 0 on the day itself. |
| date | Date | The next January 21 on or after the start date. |
| weekday | Day of the week | The weekday of that date. |
| weeks | In weeks | The same number of days in weeks and days. |

## Method

Find the first January 21 on or after the start date, then count the days from the start date to it.

## Assumptions

- January 21 comes every year, so the count is never more than 365 days.
- The start date itself is not counted: from the day before January 21, the count is 1; on January 21 itself, it is 0.
- Start dates from January 1, 1900 to December 31, 2400 work for the count to January 21, the range the date field accepts.
- Today is the date on your own device, so the count to January 21 changes at midnight where you are. Dates are whole calendar days, so a daylight-saving change never adds or loses a day.

## Worked examples

1. from = 2027-01-21 gives date = 2027-01-21, days = 0. Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years).
2. from = 2027-01-01 gives date = 2027-01-21, days = 20. Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years).
3. from = 2027-01-22 gives date = 2028-01-21, days = 364. Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years).

## FAQ

### What day of the week is January 21?

Wednesday, January 21, 2026; Thursday, January 21, 2027; Friday, January 21, 2028. The weekday of January 21 moves on one day a year, or two when a February 29 falls between.

### What day of the year is January 21?

January 21 is day 21 of the year, with 344 days after it (345 in a leap year).

### What season is January 21 in?

In the Northern Hemisphere, January 21 is in winter in every year from 2026 to 2035; in the Southern Hemisphere, it is summer. Seasons here start on the astronomical equinoxes and solstices, dated in US Eastern Time.

### Is January 21 a US federal holiday?

In some years. Martin Luther King Jr. Day, a US federal holiday that moves with the weekday, falls on January 21 in 2030, 2036, and 2041.

### How are the days until January 21 counted?

From the start date to January 21, without counting the start date: from January 20 the count is 1, and on January 21 it is 0. The day after, it moves on to the next January 21: from January 22, 2026, that is January 21, 2027, 364 days away.

## Sources

- 5 U.S.C. 6103 (federal holidays; weekend rule in 6103(b) and Executive Order 11582). Checked against OPM holiday schedules.
- Equinoxes and solstices: Jean Meeus, Astronomical Algorithms (2nd ed., 1998), chapter 27, checked against the US Naval Observatory.