Roman numeral dates

Nothing in a Roman numeral date marks which part is the day. XII.V.MMXIX is 12 May 2019 read day first, and 5 December 2019 read month first. Both readers are following a real convention. The W3C's note on date formats puts it this way: “The format MM/DD/YY is unique to the United States (but sometimes used in Canada, too, which can obviously create some confusion there). Most of Europe uses DD/MM/YY.”

A date can only be misread when both the day and the month are twelve or under and they are different numbers. In 2026 that is 132 of its 365 days, worked out by writing every day of the year day first and reading each one back. The first tool warns you when the date you pick is one of them, and the second lists every reading it finds.

Year first is the order the same note offers as the neutral one: “ISO 8601 specifies a format of YYYY-MM-DD. 2003-04-02 is clearer than 03/04/02.” A year written in full cannot be mistaken for a day or a month.

Every reading. It reads the three numerals day first, month first and year first, keeps each reading that is a real day on the calendar, leap years included, and says so when there is more than one. The day of the week beside each reading is worked out on the Gregorian calendar, the one in general use today.

The spelling of each numeral. Each part goes through the same reader as the Roman numeral converter, so a numeral that is readable but not written the standard modern way is read, and its standard spelling is shown beside it. Common Roman numeral mistakes explains why each of these is not the standard form.

A short year. A year written as XIX is 19, not 2019. The checker reads it as written and shows the full year both ways.

The separators. Any mark between the parts is read, and two different marks in one date are pointed out. Without any separator the letters stop being one date: XIIVMMXIX can be cut into three numerals in more than one place, and the ways of reading it give four different days in 2019: 11 April 2019, 12 May 2019, 4 November 2019, 5 December 2019.

The image is drawn on a canvas in your browser and saved straight from it, as a PNG of 1,600 by 800 pixels. Nothing is uploaded. It uses the serif typeface already on your device, so it looks slightly different from one device to another; an engraver or a tattoo artist will set the letters in their own lettering in any case, and the image is there to make the letters and their order unmistakable. Leaving the date in words underneath is the simplest way to make sure it is read the way you meant.