Reading Level Checker
Analyze any text for reading ease, grade level, and readability score. Instant results.
The reading level checker analyzes text using three standardized readability formulas: the Flesch Reading Ease score (0-100, higher is easier), the Flesch-Kincaid Grade Level (US school grade equivalent), and the Gunning Fog Index (years of education required). It also provides nine text statistics including word count, sentence count, syllable count, and estimated reading time.
How to Use the Reading Level Checker
- 1Paste your text into the input box, or click Load example text to try a sample.
- 2Click Analyze Text to instantly calculate all readability scores.
- 3Review the Flesch Reading Ease score, Flesch-Kincaid grade level, and Gunning Fog Index.
- 4Check the Text Statistics panel for word count, sentence count, syllables, and reading time.
- 5Revise your text to shorten sentences or replace complex words to improve readability.
Worked Example: Scoring a Simple Sentence by Hand
Take: "The cat sat on the mat. It was a sunny day." That's 11 words across 2 sentences, and every word is one syllable except "sunny" (2) — 12 syllables total. So the average sentence length is 11 ÷ 2 = 5.5 words, and syllables per word is 12 ÷ 11 ≈ 1.09.
Flesch Reading Ease = 206.835 − 1.015 × 5.5 − 84.6 × 1.09 ≈ 108.96. The scale tops out at 100, so the tool clamps it there and labels the text "Very Easy."
Flesch-Kincaid Grade = 0.39 × 5.5 + 11.8 × 1.09 − 15.59 ≈ −0.57. Grade levels can't be negative, so the tool floors it at 0.0 — "Elementary School." Both formulas use the exact same two inputs (sentence length and syllables per word); they just weight them differently.
Worked Example: A Technical Sentence, and What Happens When You Rewrite It
Compare a dense, single-sentence definition against the same idea split into two shorter sentences with simpler words:
| Version | Flesch Ease | FK Grade | Fog Index |
|---|---|---|---|
| "Photosynthesis is the fundamental biological process by which organisms convert light energy into chemical energy." (1 sentence, 15 words) | 0.0 | 18.6 | 24.7 |
| "Photosynthesis turns light into energy. Plants use it to grow." (2 sentences, 10 words) | 57.9 | 6.4 | 10.0 |
Splitting one 15-word sentence into two shorter ones cut the words-per-sentence average roughly in half, and swapping "fundamental biological process" for "turns" and "convert" for "use" dropped both the syllable count and the number of 3+ syllable "complex" words. That combination took the Flesch-Kincaid grade from graduate level (18.6) down to roughly 6th grade (6.4).
What the Score Actually Means — and Why the Three Numbers Don't Always Agree
Flesch Reading Ease and Flesch-Kincaid Grade are two different linear formulas built from the exact same two ingredients: average sentence length and average syllables per word. The Gunning Fog Index uses a related but distinct signal — the percentage of words with 3 or more syllables — so it can rate the same text a bit differently than the other two.
None of these formulas actually reads for meaning. A word like "photosynthesis" has 5 syllables and will drag the grade level up even though it's a term most middle-schoolers already know — the math can't tell the difference between a long, hard word and a long, familiar one.
What the number is genuinely useful for: it tells you which two levers to pull if you want text to read easier — shorten your sentences, and swap long words for shorter synonyms where the meaning allows. Those are the only two things any of these three scores actually measure.
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Frequently Asked Questions
What is the Flesch Reading Ease score?
Ranges 0-100. Higher scores (70-100) indicate easy text (5th-6th grade). Lower scores (0-30) indicate professional or academic text. A score of 60-70 is standard for general audiences.
What is the Flesch-Kincaid Grade Level?
Outputs a US school grade equivalent. A score of 8.0 means an 8th grader can understand the text. Calculated from average sentence length and syllables per word.
What is the Gunning Fog Index?
Estimates years of formal education needed to understand the text. A score of 12 = high school senior. Scores above 17 are graduate level.
What reading level should I aim for?
General audiences: Flesch 60-70, FK Grade 7-8. Academic writing: Flesch 30-50. Newspapers: Grade 6-8. Children content: Flesch 80-90.