Readability Score Calculator
Paste English text to calculate its Flesch Reading Ease score, estimated U.S. grade level, sentence length and syllable density. The checker updates as you edit and explains which parts of the writing make it easier or harder to read. Everything runs locally in your browser.
- 100% free
- Private & safe
- Runs in your browser
Why use Readability Score Calculator?
Readability scores turn the vague feeling that writing is “too dense” into concrete numbers — sentence length, syllable load and an estimated grade — so you know exactly what to simplify.
- Runs instantly in your browser — nothing to install, nothing uploaded.
- Completely free, with no account, no watermarks and no usage limits.
- Handles Works best on English prose of at least a few sentences — short samples can swing the score.; Lists, code, tables and non-English text produce unreliable results.; Text is analyzed locally in your browser and is never uploaded..
- Paste or type your English text, or load the built-in sample.
- Works on any device — desktop, tablet and phone — and is fully keyboard accessible.
What it can do — and its limits
- Calculates Flesch Reading Ease, commonly interpreted on a 0–100 scale, and the Flesch–Kincaid grade level as you type.
- Reports average words per sentence, syllables per word and the share of complex (3+ syllable) words.
- Flags the three hardest sentences and counts sentences longer than 25 words.
- Tailors recommendations to a General web, Marketing, Students or Technical audience.
- Shows a visible interpretation table before you enter text; runs entirely in your browser.
How to use Readability Score Calculator
- Paste or type your English text, or load the built-in sample.
- Pick a target audience (general web, marketing, students or technical) to tailor the advice.
- Read the Reading Ease gauge, grade level and sentence/syllable stats as you edit.
- Review the hardest sentences and recommendations, simplify, and re-check instantly.
Examples
- Checking a blog post targets plain English (Reading Ease 60–70) before publishing.
- Simplifying a product description so it reads at about grade 7 for a marketing audience.
- Finding the three hardest sentences in an email and rewriting them shorter.
Worked example
Input
“The utilization of an excessive quantity of polysyllabic terminology invariably diminishes comprehensibility.” The calculator returns 12 words, a Reading Ease score of −87.3 and a Grade Level of 28.4. The sentence is classified as very difficult because most of its words contain several syllables.
Output
Rewritten as “Too many long words make writing hard to understand,” the sentence contains 9 words and receives a Reading Ease score of 75.5 and a Grade Level of 5.0. It communicates the same basic idea with shorter, more familiar words.
Shorter sentences and fewer multi-syllable words move both scores at once.
Input requirements
- Works best on English prose of at least a few sentences — short samples can swing the score.
- Lists, code, tables and non-English text produce unreliable results.
- Text is analyzed locally in your browser and is never uploaded.
Flesch Reading Ease vs. Flesch–Kincaid Grade Level
Both formulas use the same two inputs — average sentence length and average syllables per word — but express the result differently.
| Metric | Output | Higher number means | Formula |
|---|---|---|---|
| Flesch Reading Ease | 0–100 score | Easier to read | 206.835 − 1.015 × (words/sentence) − 84.6 × (syllables/word) |
| Flesch–Kincaid Grade Level | US school grade | Harder to read | 0.39 × (words/sentence) + 11.8 × (syllables/word) − 15.59 |
Limitations
- Readability formulas measure word and sentence length only — not meaning, structure, tone or how familiar a topic is to your reader.
- The U.S. Agency for Healthcare Research and Quality advises treating scores as diagnostic indicators, not proof that readers will understand the text.
- Syllable counting is estimated algorithmically and can be off for unusual words, names and abbreviations.
- Scores are designed for English prose; lists, code, tables and non-English text produce unreliable results.
- A very short sample can swing the score dramatically — analyze a representative passage.
Sources & references
- AHRQ — Use readability formulas as a guide (Tip 6)
- Kincaid et al. (1975) — Derivation of New Readability Formulas for Navy Enlisted Personnel
Last verified August 2026.
Frequently asked questions
What is a good Flesch Reading Ease score?
For general web content, aim for 60–70 (plain English, about US grade 8). Marketing copy often targets 70+, while technical writing for experts can sit lower.
What is the difference between Reading Ease and Grade Level?
Both use average sentence length and syllables per word. Reading Ease is a 0–100 score where higher is easier; the Flesch–Kincaid Grade Level maps the same inputs to a US school grade where higher is harder.
How can I improve my readability score?
Shorten long sentences, prefer short everyday words over multi-syllable ones, use active voice, and break dense paragraphs into shorter ones. Re-check after each edit.
Do readability scores guarantee my writing is clear?
No. They estimate difficulty from word and sentence length only and do not measure meaning, organization or topic familiarity. Use them as a guide alongside real reader feedback.
Is my text uploaded anywhere?
No. All analysis runs locally in your browser; your text is never sent to a server.