BYTETOOLS

LIX Readability Calculator

Calculate the LIX readability index and the companion RIX score for any text, with difficulty bands, school-year equivalents and the long words highlighted.

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LIX
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RIX
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RIX school year
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Words
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Sentences
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Long words (7+ letters)

Paste at least one sentence to see the LIX and RIX scores.

LIX difficulty bands

LIXDifficultyTypical text
Under 25Very easyChildren's books
25 – 34EasyFiction and popular magazines
35 – 44MediumNormal newspaper text
45 – 54DifficultFactual and official prose
55 and overVery difficultTechnical, legal and bureaucratic text

RIX to school year (Anderson, 1983)

RIX ≤ 0.2 → 1RIX ≤ 0.3 → 2RIX ≤ 0.5 → 3RIX ≤ 0.8 → 4RIX ≤ 1.3 → 5RIX ≤ 1.8 → 6RIX ≤ 2.4 → 7RIX ≤ 3 → 8RIX ≤ 3.7 → 9RIX ≤ 4.5 → 10RIX ≤ 5.3 → 11RIX ≤ 6.2 → 12RIX ≤ 7.2 → CollegeRIX > 7.2 → College graduate

What is the LIX Readability Calculator?

LIX — läsbarhetsindex — is the readability index used across Scandinavia and much of northern Europe, and it works on any language that separates words with spaces.

  • LIX score with Björnsson's published very-easy to very-difficult bands
  • RIX score with Anderson's school-year conversion table
  • Adjustable long-word threshold for other languages
  • Full list of the long words counted, with repeat counts
  • Sentence, word and long-word statistics alongside the score
  • 100% in-browser — your text is never uploaded

How to use the LIX Readability Calculator

  1. 1

    Paste your text into the input box.

  2. 2

    Leave the long-word threshold at 6 letters for the original definition, or raise it for a language with longer words.

  3. 3

    Read the LIX score and its difficulty band, from very easy to very difficult.

  4. 4

    Check the RIX score for a school-year equivalent using Anderson's conversion table.

  5. 5

    Review the highlighted long words to see which vocabulary is pushing the score up.

About the LIX Readability Calculator

LIX — läsbarhetsindex — is the readability index used across Scandinavia and much of northern Europe, and it works on any language that separates words with spaces. This calculator gives you the LIX score, the difficulty band it falls into, and Anderson's companion RIX score with its school-year equivalent, all recalculated as you type.

The formula is deliberately simple: average sentence length plus the percentage of long words, where a long word is one with more than six letters. That makes it far easier to apply to non-English text than syllable-based formulas like Flesch or SMOG. You can change the long-word threshold if your language runs longer, and every long word the tool counted is listed so you can see what is driving the score.

All the counting happens locally in your browser — no text is uploaded to a server, nothing is stored, and the calculator keeps working offline once the page has loaded.

Frequently asked questions

What is a good LIX score?

Under 25 is children's-book territory, 25 to 34 reads like popular fiction, 35 to 44 matches normal newspaper text, 45 to 54 is the level of official and factual prose, and anything over 55 reads as technical or bureaucratic.

How is LIX calculated?

LIX equals the average sentence length — words divided by sentences — plus the percentage of long words, where long means more than six letters. A text averaging 18 words per sentence with 24% long words scores 42.

What is the difference between LIX and RIX?

RIX is Anderson's simplification: long words divided by sentences, with no percentage term. It converts directly to a US school grade through a published table, which makes it easier to explain to an English-speaking audience than a raw LIX number.

Does LIX work for languages other than English?

Yes, and that is its main advantage. Because it counts letters rather than syllables, LIX works on Swedish, Danish, German, Dutch and other space-separated languages. German and Swedish compound nouns push scores higher, so compare texts within a language rather than across languages.

Why does my newspaper article score around 40?

That is exactly what Björnsson found — normal newspaper text clusters in the 35 to 44 band. If your article lands there, it is pitched at a general adult reader, which is usually the intention for news and marketing copy.

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