Is year's full form hyphenated in English?

Someone said In English year's full is only written with the last two numbers hyphenated. So, if I am talking about the year 2121, should I write it as twenty one twenty-one?

• This question reminded me this (meme-ish) picture... Mar 23, 2022 at 9:32

Whether to hyphenate a number above 20 is a style choice. If writing 'the year 2121' in words, (e.g. in reported speech), either hyphenate both, or neither. Don't hyphenate just one. The more formal choice is to use hyphens in numbers from 21 to 99.

In the year twenty-five twenty-five. If man is still alive, Terence sings.

There but the, (novel by Ali Smith). Terence is singing part of a famous 1969 hit song by Zager and Evans (the title and lyrics have '2525').

NUMBERS: from twenty-one to ninety-nine, when spelled out, are hyphenated.

University style guide

• I see, thank you very much! Mar 23, 2022 at 9:09

While they are spoken that way, years are rarely written as words unless it is for stylistic reasons. You'll notice there is a huge inconsistency in the way that we say them - for example, the year 2012 could be said as either 'two thousand and twelve' or 'twenty twelve'. Writing them as numerals allows people to read them as they would personally say them. Also note that examples such as 'twenty-twelve' do not make any mathematical sense in the way that 'two thousand and one' does. So, there are no hard rules of either grammar or mathematics that dictate the way these are said or written as words, if that is your choice to do so.

That said, consider one reason for hyphenating any words - to avoid ambiguity.

For example:

Twenty two thirty five

Without hyphens, this is just a series of numbers. Does the twenty join with the two, or does the two join with the thirty? You might say "two thirty" if you were telling the time! Your suggestion to use just one hyphen doesn't really make any sense, because any good that the hyphen does still leaves ambiguity.

According to the 'Number Word' website, a resource for converting numbers to words in various formats including years, the standard for both American and British English would be to write your example of 2121 as:

Twenty-one twenty-one

• That's detailed and well-reasoned. Thank you! Mar 23, 2022 at 9:44
• I would add that an important thing, having chosen a style, is to be consistent. Don't write 'the year twenty-one thirty-six' and later on write 'the year twenty two forty four'. Mar 23, 2022 at 11:35