Sticky dates

How it works

A sticky date on a calendar is a date you pin. You write it once, and it is still there when the week turns. Counting those pins is ordinary date arithmetic: name the year, name the month, name the day, then walk forward one square at a time.

The mark does not change the length of the month. June still has 30 days. February still has 28, or 29 in a leap year. A sticky date is a flag on a square that already existed. If you mark 31 April, the calendar has no such square to hold the flag.

People also use sticky dates for a run of days that should travel together: a three-day trip, a weekend visit, a block of exams. Count the span by subtracting the start date from the end date. That subtraction is the gap. Listing every date from start through end is the inclusive list, which is larger by one.

Write the year. “The 12th” without a year is not a count. Write the month length you actually have, not a guessed average of 30. Say whether you want the gap until the day, or the list of days including both ends.

If the date already passed this year, the next sticky copy is next year. The kitchen meaning is separate. Sticky dates are also a fruit, and sticky date pudding is a dessert built around that fruit. Neither lengthens November. You can count pieces on a plate; that is not a calendar. You can count calendar squares; that is not a pudding. Keep the two jobs apart and both answers stay honest.

Dates that stay put, and dates that repeat

Some sticky dates repeat every year on the same month and day: a birthday, an anniversary, a civic holiday that sits on a fixed date. Leap day is the awkward sibling. 29 February exists only in a leap year. In other years that sticky mark has no square, and people who keep a 29 February birthday choose 28 February or 1 March as the civil stand-in. That is a choice of label, not a new month length.

Other sticky dates walk. A school term that starts on the first Monday after a date is not the same square every year. Count it by finding that Monday in the year you mean, then counting from today to that Monday. Do not reuse last year’s number. The weekday pattern moves.

A reminder that repeats every month on the 15th is twelve sticky dates in a common year, not one date visited twelve times in the same week. From 15 January to 15 February is one month; it is not always the same number of days, because months are 28, 29, 30, or 31 days long. Month-to-month sticky dates are equal in months and unequal in days. Say which unit you are using before you write the figure.

A date that never gets a square on the grid is already late. The calendar will not grow a 31 April to save a plan that was written on a day that does not exist.

Counting through a year of pins

From 3 September 2026, a sticky date of 3 September 2027 is 365 days away. 2027 is not a leap year. From 3 September 2027 to 3 September 2028 is 366 days, because 29 February 2028 sits in that span. Work the pair of dates; do not recite “a year is 365 days” as if leap day never happens.

If several sticky dates sit in one month, count them as a set of squares, not as a feeling that “the month is busy.” Five marked days in a 31-day month leave 26 unmarked. The month did not shrink. The marks did not merge unless you chose to treat them as one span.

When two sticky dates collide on the same square — a birthday and a bill on the 15th — that is still one calendar date. The count of dates is one. The count of tasks on that date is two. Mixing those counts is how a day looks twice as long as it is.