# Days until January 31

Counts the days from today, or any date you choose, to the next January 31, with its day of the week.

- Page: https://www.acalculator.org/days/days-until-january-31
- JSON spec: https://www.acalculator.org/days/days-until-january-31.json
- Version: 4438bd8bdcc8

## 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 123 days until January 31 on Sunday, January 31, 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 31 | Whole days from the start date to the next January 31; 0 on the day itself. |
| date | Date | The next January 31 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 31 on or after the start date, then count the days from the start date to it.

## Assumptions

- January 31 comes every year, so the count is never more than 365 days.
- The start date itself is not counted: from the day before January 31, the count is 1; on January 31 itself, it is 0.
- Start dates from January 1, 1900 to December 31, 2400 work for the count to January 31, the range the date field accepts.
- Today is the date on your own device, so the count to January 31 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 = 2027-01-31 gives date = 2027-01-31, 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 = 2027-01-31, days = 30. Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years).
3. from = 2027-02-01 gives date = 2028-01-31, 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 31?

Saturday, January 31, 2026; Sunday, January 31, 2027; Monday, January 31, 2028. The weekday of January 31 moves on one day a year, or two when a February 29 falls between.

### What day of the year is January 31?

January 31 is day 31 of the year, with 334 days after it (335 in a leap year).

### What season is January 31 in?

In the Northern Hemisphere, January 31 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 31 a US federal holiday?

No. No US federal holiday falls on January 31. The next one in the calendar after January 31 is Washington's Birthday (Presidents' Day), which falls between February 15 and February 21.

### How are the days until January 31 counted?

From the start date to January 31, without counting the start date: from January 30 the count is 1, and on January 31 it is 0. The day after, it moves on to the next January 31: from February 1, 2026, that is January 31, 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.