How to write dates in words correctly
US versus international date order, the ordinal suffix rule that trips people up, and how to spell out dates cleanly in formal writing.
Two orders, one source of confusion
The biggest ambiguity in dates is not the words but the order of the numbers. Written as digits, 06/11/2026 means the 11th of June to an American reader and the 6th of November to most of the rest of the world. Spelling the month out removes that ambiguity entirely, which is the main reason contracts and formal letters write June 11th, 2026 or 11 June 2026 instead of a string of slashes. Choosing month-day-year or day-month-year is really about matching your reader's convention.
The ordinal suffix rule
English adds st, nd, rd, or th to a day number based on its last digit: 1st, 2nd, 3rd, then 4th through 20th all take th. The catch is the teens. Eleven, twelve, and thirteen take th despite ending in one, two, and three, giving 11th, 12th, and 13th. After 20 the pattern resumes, so you get 21st, 22nd, 23rd, and 24th. Getting this right by hand is easy to slip on, which is why the tool applies the standard rule for every day of the month.
Dates in contracts and formal writing
In legal and official documents the fully spelled-out date is preferred because it cannot be altered as easily as a digit and cannot be misread across regions. US legal style often writes the ordinal, as in the 11th day of June, 2026, while British and international style tends to drop the ordinal for 11 June 2026. Invitations lean the other way and favour the long, ordinal form for its formality. Knowing your document type tells you which toggles to set.
Long versus short month names
A long month name such as September reads well in prose and formal correspondence, while a short form such as Sep saves space in tables, ledgers, and file names where a fixed three-letter width keeps columns aligned. The meaning is identical; the choice is about tone and layout. For anything a person will read as a sentence, the long form usually looks more polished, so it is the default here.