Free Reading Level Calculator
Paste any text (an article, worksheet, book excerpt, or essay) and get instant readability scores. Flesch-Kincaid grade level, Gunning Fog index, Lexile estimate, and recommended grade level. No sign-up, no limits.
How Reading Level Formulas Work
Every readability formula tries to solve the same problem: how do you put a number on how hard a piece of text is to read? The answer, it turns out, comes down to two surprisingly reliable signals, sentence length and word complexity.
Flesch-Kincaid Grade Level
Developed in the 1970s for the U.S. Navy to evaluate technical manuals, the Flesch-Kincaid Grade Level formula maps text onto U.S. school grade equivalents. A score of 6.0 means an average 6th grader can read it comfortably. The formula weighs both average sentence length and average syllables per word. Most newspaper writing targets a grade 7-9 score. Legal documents frequently score above 15.
Gunning Fog Index
Robert Gunning developed the Fog Index in 1952 for business writing. Its key insight is that polysyllabic words, those with three or more syllables , are a stronger indicator of text difficulty than syllable averages alone. The formula adds the percentage of complex words to the average sentence length and multiplies by 0.4. Anything above 12 is considered difficult for general audiences; above 17 requires graduate-level education to parse on first reading.
Lexile Measures
Unlike grade-level scores, Lexile measures (e.g., 850L) describe both text difficulty and reader ability on the same scale. This makes them especially useful for matching students to books. A student reading at 850L is well matched with texts in the 700L–1000L range. The Lexile estimate in this calculator is derived from the Flesch-Kincaid grade level and is approximate, official Lexile measurements require MetaMetrics analysis.
Practical Uses for Teachers
- Curriculum materials: Check that textbook excerpts, handouts, and articles are at the appropriate level for your grade.
- Differentiated reading: Find the score gap between your grade-level materials and below-grade-level texts to plan scaffolding.
- Student writing feedback: Paste a student essay to give data-backed feedback on sentence variety and vocabulary complexity.
- Assessment passages: Verify that reading comprehension passages align with the grade level you are testing.
Flesch Reading Ease Score Reference
The Flesch Reading Ease score runs 0–100. Higher is easier.
| Score | Level | Typical Audience |
|---|---|---|
| 90–100 | Very Easy | Grade 5 students |
| 80–89 | Easy | Grade 6 students |
| 70–79 | Fairly Easy | Grade 7 students |
| 60–69 | Standard | Grade 8–9 students |
| 50–59 | Fairly Difficult | High school students |
| 30–49 | Difficult | College students |
| 0–29 | Very Confusing | Graduate / Professional |
Frequently Asked Questions
Common questions about readability formulas and how to use this calculator.
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