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. Free with a teacher account, 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 to 9 students |
| 50–59 | Fairly difficult | High school students |
| 30–49 | Difficult | College students |
| 0–29 | Very confusing | Graduate or professional |
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How to check the reading level of a text
- Paste a paragraph or more, at least 30 words.
- Press Analyse text.
- Read the grade level, the Lexile estimate and the recommended reading level.
- Copy the results or print them with the text statistics.
Questions teachers ask
What is the Flesch-Kincaid grade level?
The Flesch-Kincaid Grade Level formula converts readability into a U.S. school grade equivalent. A score of 8.0 means the text is readable by an average 8th grader. The formula considers two factors: average sentence length and average number of syllables per word. Longer sentences and more polysyllabic words produce higher (harder) scores.
What is the Gunning Fog Index?
The Gunning Fog Index estimates the years of formal education needed to understand the text on the first reading. Like Flesch-Kincaid, it weights sentence length and complex words (words with three or more syllables). A score of 12 targets high school graduates; anything above 17 is considered college-graduate level.
What is a Lexile measure and why does it matter?
A Lexile measure is a numeric score (e.g., 850L) that describes both the text complexity and the reader ability on the same scale. Schools use Lexile ranges to match students with books at their just-right level, challenging enough to build skills without causing frustration. This calculator provides an approximate Lexile estimate derived from the Flesch-Kincaid grade level.
How do I lower the reading level of my text?
The two most effective changes are shortening sentences and replacing long words with shorter synonyms. Aim for an average sentence length under 20 words and limit three-syllable words to under 10% of your vocabulary. Reading your text aloud helps you spot the sentences that feel too long.
How many words do I need for an accurate result?
Most readability formulas require at least 100 words to produce stable scores. Fewer words amplify the effect of any single long sentence or complex word. For the most reliable results, analyze complete paragraphs or full articles rather than individual sentences.
Which readability formula should I use?
For general K-12 curriculum materials, Flesch-Kincaid is the most widely used and recognized standard in U.S. schools. For business and journalism writing, the Gunning Fog Index is common because it specifically flags polysyllabic vocabulary. Using both gives you a more complete picture of your text's complexity.
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