# Days until Monday

Counts the days from today, or any date you choose, to the next Monday, with its date and the Monday after it.

- Page: https://www.acalculator.org/days/days-until-monday
- JSON spec: https://www.acalculator.org/days/days-until-monday.json
- Version: 6e64c93b16a0

## 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 5 days until Monday, October 5, 2026.

## Inputs

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

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| days | Days until Monday | Whole days from the start date to the next Monday; 0 when the start date is a Monday. |
| date | Next Monday | The next Monday on or after the start date. |
| after | The Monday after | The Monday one week later. |

## Method

Days until Monday = (1 − the start date’s weekday + 7) mod 7, with Sunday = 0, Monday = 1, …, Saturday = 6.

## Assumptions

- On a Monday, the count is 0; the Monday after is 7 days away.
- The start date itself is not counted: from the day before, the count is 1.
- Dates are calendar days with no time of day, so a time zone or a daylight-saving change never adds or loses a day.
- Start dates from January 1, 1900 to December 31, 2400 work.

## Worked examples

1. from = 2026-09-28 gives date = 2026-09-28, days = 0. Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years).
2. from = 2026-12-31 gives date = 2027-01-04, days = 4. Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years).
3. from = 2028-02-27 gives date = 2028-02-28, days = 1. Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years).

## FAQ

### How many days until Monday from each day of the week?

From Monday, 0; from Tuesday, 6; from Wednesday, 5; from Thursday, 4; from Friday, 3; from Saturday, 2; from Sunday, 1. On a Monday the count is 0, and the Monday after is 7 days away.

### What if today is Monday?

Then the count is 0, because the next Monday on or after today is today. The page also shows the Monday after it, 7 days later.

### How many Mondays are in a year?

A year of 365 days is 52 weeks and 1 day, so the weekday of January 1 comes 53 times and every other weekday 52 times; in a leap year, the weekdays of January 1 and 2 come 53 times. 2026 has 52 Mondays, and 2027 has 52.

### How are the days until Monday counted?

From the start date (today, unless you change it) to the next Monday, without counting the start date, in calendar days. Weekends and holidays count like any other day.