Grade Level Scores

These scores estimate what school grade can read your text. A score of 8 means an 8th grader should understand it.

The Four Metrics

Metric	What It Measures	Best For
Flesch-Kincaid	Words per sentence, syllables	General docs
ARI	Characters per word	Tech content
Gunning Fog	Long words (3+ syllables)	Business writing
Coleman-Liau	Character counts	Academic papers

Which One?

Start with Flesch-Kincaid. It works well for most content. Add ARI if you write technical docs with code terms.

Flesch-Kincaid Grade Level

The most common metric. It looks at sentence length and syllable count.

What affects it:

• Longer sentences raise the score
• Words with more syllables raise the score

Target: Grade 8-12 for most docs.

ARI (Automated Readability Index)

Uses character count instead of syllables. This makes it better for technical content. Code terms often have many characters but few syllables.

What affects it:

• More characters per word raise the score
• Longer sentences raise the score

Target: Grade 10-14 for technical docs.

Why ARI for Tech Docs?

Words like "config" and "param" are short in syllables but long in characters. ARI catches this better than other metrics.

Gunning Fog Index

Counts "complex words": those with three or more syllables. Common endings like "-ing" and "-ed" don't count.

What affects it:

• More complex words raise the score
• Longer sentences raise the score

Target: Grade 12-14 for business content.

Picking the Right Metric

Your Content	Primary Metric	Secondary
User guides	Flesch-Kincaid	-
API docs	ARI	Flesch-Kincaid
Business docs	Gunning Fog	Flesch-Kincaid
Tutorials	Flesch-Kincaid	ARI

Multiple Metrics

You can check more than one. Use max_grade for Flesch-Kincaid and max_ari for ARI in your config.