LIX measures readability using sentence length and proportion of long words (>6 letters). Works for many European languages.
Use LIX when working with Germanic or Romance languages (Swedish, German, Dutch, Norwegian, Danish, Spanish, French, Italian, Portuguese). It was specifically designed not to depend on English-specific syllable patterns, so it generalises better than Flesch-family formulas.
LIX is the closest international equivalent of Flesch Reading Ease. Compared to Coleman–Liau, LIX uses word length thresholds (>6 letters) rather than averages, making it slightly less smooth but more interpretable.
LIX (Läsbarhetsindex) is a Swedish readability index created by Carl-Hugo Björnsson in 1968.
It combines average sentence length with the percentage of "long" words — words with more than 6 letters.
It generalises better to many European languages than the Flesch-family formulas, which are tuned for English.
LIX was designed for Swedish but works reasonably for Germanic and Romance languages: English, German, Dutch, Spanish, French, Italian, Portuguese.
In LIX, any word longer than 6 characters.
Scores below about 30 read as very easy, 30 to 50 as standard prose, 50 to 60 as fairly difficult, and above 60 as hard, technical text. Children's books typically sit under 30 while academic writing often exceeds 50.
LIX uses sentence length and the percentage of long words (over six letters) rather than syllables, which makes it work across many European languages. Flesch relies on syllable counts calibrated only for English.
Input
Det är en mycket lång mening med flera långa ord och tydliga underordnade satser.
Output
LIX: 39 — Medium / standard newspaper prose.
LIX combines average sentence length with the percentage of long (>6 letter) words. Most European-language news lands in the 30s–40s, and this Swedish sentence is squarely in that range.
Classic 0–100 readability score.
readabilityU.S. grade level for your text.
readabilityPenalises complex (3+ syllable) words.
readabilityHealth & medical text grade level.