Gera Tools

Finnish LIX Readability Score

LIX readability for Finnish — long agglutinative words skew scores

Applies the LIX readability formula to Finnish, with a note that agglutinative compounds inflate the long-word percentage, computed live in your browser.

Why is my Finnish LIX score so high?

Finnish is agglutinative, so inflection and compounding produce long words like lukukelpoisuusindeksi. These count as long words, inflating the long-word percentage and pushing the LIX value higher than an English equivalent.

LIX is the Scandinavian readability index, and it can be applied to Finnish because it relies only on word length and sentence length rather than syllables. The important caveat is that Finnish is agglutinative, so its words are unusually long and the index reads higher than for analytic languages like English.

How it works

LIX uses total words, total sentences, and the count of long words. A long word has more than six letters. The score is:

LIX = (words / sentences) + (longWords × 100 / words)

The first term is the average sentence length in words. The second is the percentage of long words. In Finnish, case endings such as the inessive or elative, plus heavy noun compounding, push many ordinary words past seven letters, so the long-word percentage is structurally elevated.

Tips and example

A short Finnish word like “talo” stays small, but its inflected form “taloissammekin” or a compound like “lukukelpoisuusindeksi” easily exceeds the long-word threshold. Because of this, a perfectly clear Finnish text can still score in the difficult band. Compare scores against other Finnish texts rather than against English benchmarks. To reduce a score, shorten sentences first, since average sentence length feeds straight into the formula, and prefer simpler vocabulary where the grammar allows.