# Days until March 18

Counts the days from today, or any date you choose, to the next March 18, with its day of the week.

- Page: https://www.acalculator.org/days/days-until-march-18
- JSON spec: https://www.acalculator.org/days/days-until-march-18.json
- Version: 130f3af4fbab

## 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 169 days until March 18 on Thursday, March 18, 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 March 18 | Whole days from the start date to the next March 18; 0 on the day itself. |
| date | Date | The next March 18 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 March 18 on or after the start date, then count the days from the start date to it.

## Assumptions

- March 18 comes every year, so the count is never more than 365 days.
- The start date itself is not counted: from the day before March 18, the count is 1; on March 18 itself, it is 0.
- Start dates from January 1, 1900 to December 31, 2400 work for the count to March 18, the range the date field accepts.
- Today is the date on your own device, so the count to March 18 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 = 2027-03-18 gives date = 2027-03-18, 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 = 2027-03-18, days = 76. Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years).
3. from = 2027-03-19 gives date = 2028-03-18, days = 365. 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 March 18?

Wednesday, March 18, 2026; Thursday, March 18, 2027; Saturday, March 18, 2028. The weekday of March 18 moves on one day a year, or two when a February 29 falls between.

### What day of the year is March 18?

March 18 is day 77 of a common year and day 78 of a leap year, such as 2028. Either way, 288 days of the year come after it.

### What season is March 18 in?

In the Northern Hemisphere, March 18 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 March 18 a US federal holiday?

No. No US federal holiday falls on March 18. The next one in the calendar after March 18 is Memorial Day, which falls between May 25 and May 31.

### How are the days until March 18 counted?

From the start date to March 18, without counting the start date: from March 17 the count is 1, and on March 18 it is 0. The day after, it moves on to the next March 18: from March 19, 2026, that is March 18, 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.