Why are the first two ordinals irregular?

Ensimmäinen (first) and toinen (second) are suppletive forms unrelated to the cardinals yksi and kaksi, much like English first and second. From third onward the ordinals follow a regular pattern: kolmas, neljäs, viides, and so on.

Why does this tool only show one form?

Finnish ordinals are adjectives that inflect across all 15 grammatical cases and agree with their noun. Showing every case for every number would be overwhelming, so the tool gives the nominative, which is the dictionary citation form you build the other cases from.

How are the teens formed?

Ordinals 11 to 19 use the genitive of the unit ordinal plus toista: 11 is yhdestoista, 12 is kahdestoista, 13 is kolmastoista. The genitive stem (yhdes-, kahdes-) is why the form differs from the cardinal teens.

How do compound ordinals like 21st work?

Both parts are ordinals and join into one word: 21 is kahdeskymmenesensimmäinen and 32 is kolmaskymmenestoinen. Unlike English, every component is inflected as an ordinal, not just the last.

What range is supported?

Positions 1 to 9999, covering units, teens, tens, hundreds, and thousands. The trailing dot Finnish uses after a numeral ordinal (1.) is accepted and ignored.

Finnish Ordinal Words

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This tool turns a number into its Finnish ordinal word, the form you use for ranking and dates such as “the third” or “the twenty-first”.

How it works

Finnish ordinals start with two irregular forms and then become regular:

1  ensimmäinen   6  kuudes
2  toinen        7  seitsemäs
3  kolmas        8  kahdeksas
4  neljäs        9  yhdeksäs
5  viides       10  kymmenes

The teens use the genitive of the unit ordinal plus toista, so 11 is yhdestoista and 14 is neljästoista. Tens combine the unit ordinal with kymmenes (kahdeskymmenes = 20th), hundreds use sadas, and thousands use tuhannes. Compound positions close up into one word with every part inflected: 21st is kahdeskymmenesensimmäinen.

Tips and notes

The output is the nominative citation form. In a real sentence the ordinal agrees with its noun and takes the case the sentence requires — genitive ensimmäisen, partitive ensimmäistä, inessive ensimmäisessä, and so on across all 15 cases. Finnish also writes ordinals as a digit plus a dot (1. kerros = “first floor”), which this tool accepts as input. For plain counting numbers use the Finnish number-to-words tool.