Laesbarhedsindex (LIX) readability formula

The Laesbarhedsindex (LIX) readability formula is useful because it can be used on documents of any Western European language. This test calculates an index score of a text sample based on sentence length and number of long words (i.e., words containing seven or more characters).

The LIX Formula

LIX = W/S+(100*LW)/W

Where:

LIX LIX index score

W Number of words

LW Number of long words (7+ characters)

S Number of sentences

LIX Index Table

0-24	Very easy
25-34	Easy
35-44	Standard
45-54	Difficult
55 and above	Very difficult

Citations

H. Björnsson and Birgit Hård af Segerstad (1979). Lix på franska och tio andra språk. Stockholm: Pedagogiskt centrum, Stockholms skolförvaltning.

Anderson, Jonathan (1981). 'Analysing the Readability of English and Non-English Texts in the Classroom with Lix'.