What is LIX and how is it calculated?

LIX, the Läsbarhetsindex, is a language-independent readability formula. It equals the average number of words per sentence plus the percentage of long words, where a long word has more than six letters (seven or more).

Why use LIX instead of a Flesch score for Russian?

LIX needs no syllable counting, so it avoids any language-specific syllable model and works the same way across languages. It makes a useful independent check against the syllable-based Oborneva Flesch adaptation for Russian.

What do the LIX bands mean?

Roughly: below 25 is very easy, 25 to 34 easy, 35 to 44 medium, 45 to 54 difficult, and 55 or above very difficult. Unlike Flesch, lower LIX values mean easier text.

What counts as a long word in Russian?

Any token of seven or more letters. Russian is inflectional, so case and agreement endings lengthen words; the seven-letter threshold captures genuinely heavy vocabulary while ignoring short function words.

Is my text uploaded anywhere?

No. The whole calculation runs locally in your browser in JavaScript. Your text is never sent to a server, so the tool is safe for unpublished or confidential Russian documents.

Russian LIX Readability Score

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LIX, the Swedish Läsbarhetsindex, measures readability without counting syllables, which makes it a clean, language-independent metric. This tool applies LIX to Russian and bands the result so you can judge how demanding a passage is.

How it works

The index is:

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

Words are Cyrillic tokens, sentences are counted from terminal punctuation (. ! ? …), and a long word is one with more than six letters (seven or more). The tool sums the average sentence length and the long-word percentage, then maps the total to a difficulty band — lower means easier, the opposite direction to the Flesch scale.

Example

A passage of short sentences built from common, short words lands in the very easy or easy band. Formal Russian — long sentences full of seven-plus-letter nouns, participles, and case-inflected forms — climbs into the difficult or very difficult range. Because LIX ignores syllables entirely, the score is fast, stable, and reproducible.

Notes

Use LIX as a second opinion next to the Oborneva Flesch adaptation: when both agree, you can be confident about a text’s difficulty; when they disagree, inspect the breakdown to see whether sentence length or word length is the driver. The tool runs locally in your browser.