# Days until Earth Day

Counts the days from today, or any date you choose, to the next Earth Day, with its date and day of the week.

- Page: https://www.acalculator.org/days/days-until-earth-day
- JSON spec: https://www.acalculator.org/days/days-until-earth-day.json
- Version: d140d9eac002

## Default answer

Example with the default inputs (Count from September 29, 2026) on the example date Tuesday, September 29, 2026: From September 29, 2026, there are 205 days until Earth Day on Thursday, April 22, 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 Earth Day | Whole days from the start date to the next Earth Day; 0 on the day itself. |
| date | Date | The next date of Earth Day 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 date of Earth Day on or after the start date, then count the days from the start date to it.

## Assumptions

- Earth Day is April 22 every year.
- Start dates from January 1, 1970 to December 31, 2400 work, because the first Earth Day was on April 22, 1970.
- The start date itself is not counted: from the day before, the count is 1; on the day itself, it is 0.
- Dates are calendar days with no time of day, so a time zone or a daylight-saving change never adds or loses a day.

## Worked examples

1. from = 2026-01-01 gives date = 2026-04-22, days = 111. Source: the rule written again in Python 3 (datetime); docs/progress/WP-43.md.
2. from = 2026-04-23 gives date = 2027-04-22, days = 364. Source: the rule written again in Python 3 (datetime); docs/progress/WP-43.md.

## FAQ

### When is Earth Day 2027?

Earth Day 2027 is on Thursday, April 22, 2027.

### When is Earth Day 2028?

Earth Day 2028 is on Saturday, April 22, 2028.

### How is the date of Earth Day set?

Earth Day is April 22 every year. Source: the rule written again in Python 3 (datetime).

### How are the days until Earth Day counted?

From the start date (today, unless you change it) to the date, without counting the start date. The day before, the count is 1; on the day itself, it is 0; the day after, the count moves on to the next Earth Day.

## Sources

- the rule written again in Python 3 (datetime); docs/progress/WP-43.md