Readability Checker
Score any text on six readability formulas at once, then see which sentences are dragging the grade up. Sentence length, passive voice and long-word density are broken out, because those are the three things you can actually change.
Your text
At least ten words are needed before any of these formulas mean anything.
Paste at least a paragraph and six readability formulas are scored at once, alongside the sentence-level breakdown that shows which lines are dragging the grade up.
Short answer
A readability checker scores text on formulas that count sentence length and word length and map them onto a reading difficulty. Flesch Reading Ease runs 0 to 100 and above 60 is plain English; the grade formulas return a US school year, and 8 to 10 suits most commercial writing. Readability is not a Google ranking factor and never has been. What it predicts is whether people finish the page. Average sentence length is the heaviest term in every formula here, so splitting long sentences moves the score faster than swapping words for shorter ones.
The six formulas, and what each one actually counts
They all measure the same two things in different proportions: how long your sentences are and how long your words are. The differences are in what counts as a long word.
| Formula | Returns | Counts | Best used for |
|---|---|---|---|
| Flesch Reading Ease | 0 to 100, higher is easier | Sentence length + syllables per word | The one score with a published band table |
| Flesch-Kincaid Grade | US school grade | The same inputs, rescaled | Reporting a level to a non-specialist |
| Gunning Fog | US school grade | Sentence length + share of 3-syllable words | Business and technical copy |
| SMOG | US school grade | Polysyllables per 30 sentences | Health and safety writing, the strictest here |
| Coleman-Liau | US school grade | Letters per word, no syllables | Reproducibility, since nothing is guessed |
| Automated Readability | US school grade | Characters per word + sentence length | A second syllable-free opinion |
Two of them do no guessing at all
Syllable counting is a heuristic in every tool that reports it, including this one, and it misreads names and loanwords. Coleman-Liau and ARI count letters instead, so when the syllable-based scores disagree with them, the letter-based pair is the safer read.
What the numbers mean in practice
Flesch published the bands below in 1948 and they are still the reference every tool quotes. The audience column is the useful part.
| Reading ease | Band | Audience | Typical writing |
|---|---|---|---|
| 90 to 100 | Very easy | Average 11-year-old | Children's books |
| 80 to 89 | Easy | Average 12-year-old | Consumer fiction |
| 70 to 79 | Fairly easy | Average 13-year-old | Popular magazines |
| 60 to 69 | Plain English | 13 to 15-year-old | Newspapers, good web copy |
| 50 to 59 | Fairly difficult | 16 to 18-year-old | Trade press |
| 30 to 49 | Difficult | College student | Academic and legal writing |
| 0 to 29 | Very confusing | University graduate | Journals, contracts |
Aim for 60 or above on marketing pages, guides and blog posts. Documentation can sit lower without failing anyone, because the reader arrived knowing the vocabulary. What no page benefits from is drifting into the 30s by accident.
How to raise a readability score without dumbing the copy down
Almost every point of improvement comes from four changes, and only one of them touches your vocabulary.
- Split the long sentences. A full stop where a comma was drops the grade immediately, because sentence length carries the most weight in every formula.
- Name the actor. Turning “a decision was made” into “we decided” removes words rather than adding them, which is why the passive count is worth watching.
- Cut the qualifier stack. Words like generally, typically and essentially add syllables and remove certainty at the same time.
- Break the wall into a list. Formulas do not reward structure, but readers do, and the rewrite that makes a list possible usually shortens the sentences anyway.
What not to do is replace precise terms with vague ones to win a number. Canonical does not become web address. Score the page, fix the sentences that are genuinely doing too much, and let the vocabulary stand.
Repetition is a separate problem
Readability says nothing about how often you repeat a phrase. The keyword density checker covers that, and the two together catch most of what makes a draft feel heavy.
How to check readability
Seven steps, and the fifth is where the tool earns its place over a word processor.
- 01
Paste the finished copy, not the outline
Every formula divides by the sentence count, so headings and bullet fragments pasted without their paragraphs distort the average. HTML is accepted and stripped, with block elements treated as line breaks.
- 02
Read the Flesch Reading Ease first
It is the one score with a published band table, which makes it the only number here that means something on its own. Above 60 is plain English and is the right target for most web copy.
- 03
Use the consensus grade, not one formula
The five grade formulas disagree by two or three years on the same text, because they weight syllables and letters differently. Their average is more stable than any single one of them.
- 04
Look at what is driving the score
Average sentence length is the heaviest term in every formula on this page. If the grade is high and the long-word share is normal, the sentences are the problem.
- 05
Rewrite the hardest sentences, in order
Each sentence is scored on its own and ranked. Fixing the top three usually moves the whole-page grade more than editing the other forty, because those three are pulling the average alone.
- 06
Split rather than simplify
The fastest way to drop two grade levels is a full stop where a comma was. Replacing words is slower, riskier and usually unnecessary once the sentence is short enough.
- 07
Re-score, then stop
Plain English is a floor, not a target to keep chasing. Writing down to grade 4 to win a number produces copy that reads like a warning label and helps nobody.
Readable copy still needs a result someone will click. The SERP snippet preview shows where your title and description get cut, and the meta tags generator writes the tags that carry them.
What this checker measures
Six formulas at once
Flesch, Flesch-Kincaid, Gunning Fog, SMOG, Coleman-Liau, ARI
Consensus grade
The average of the five grade scores, which is steadier than any one
Sentence-level scoring
Every sentence graded and ranked, hardest first
Passive voice detection
Flagged per sentence, since it usually means extra words
Long-sentence count
How many run past 25 words, not just the average
HTML accepted
Tags stripped, block elements treated as line breaks
Abbreviation handling
Dr. and e.g. do not get counted as sentence endings
Runs in your browser
Unpublished drafts never leave your machine
Readability is a check, not a target
Frequently asked questions
What is a readability score?
A number produced by a formula that counts surface features of text, mostly sentence length and word length, and maps them onto a reading difficulty. It measures the shape of the writing rather than whether it makes sense, which is why it is a useful check and a bad target.
What is a good Flesch Reading Ease score?
Above 60 for most web copy, which Rudolf Flesch classed as plain English readable by a 13 to 15-year-old. News writing tends to land in the 60s, academic writing in the 30s. Below 30 the text is hard work even for a specialist.
How is Flesch Reading Ease calculated?
206.835 minus 1.015 times the average sentence length, minus 84.6 times the average syllables per word. Both penalties are large, but sentence length is the term you can change fastest, because splitting one sentence in two halves its contribution.
Is readability a Google ranking factor?
No. Google has said repeatedly that it does not score pages on readability formulas, and there is no readability signal in any documented ranking system. What readability affects is whether people finish the page, which is a different and more useful thing to care about.
What reading level should I write for?
US grade 8 to 10 suits most commercial writing, including technical topics. Government and health guidance usually targets grade 6 to 8. Writing far below your audience is its own failure: readers treat oversimplified copy as thin.
Why do the six formulas give different scores?
They were built for different corpora and weight things differently. Gunning Fog and SMOG count words of three or more syllables. Coleman-Liau and ARI count letters and skip syllables entirely. A two to three grade spread on the same text is normal.
Which readability formula is the most accurate?
None of them is accurate in the way the decimal places suggest. Coleman-Liau and ARI are the most reproducible because counting letters needs no guessing, while syllable-based formulas depend on a heuristic that misreads names and loanwords. Use the consensus.
How are syllables counted?
By counting vowel groups and correcting for silent endings, which is what every readability tool does. It is a heuristic, not a dictionary, so it is wrong on some proper nouns and borrowed words. On a few hundred words those errors average out.
Does passive voice affect readability scores?
Not directly. No formula on this page detects voice at all. It is flagged separately because passive constructions are usually longer than the active version, and sentence length is what the formulas actually measure.
What sentence length should I aim for?
An average of 15 to 20 words, with variety around it. A page where every sentence is 12 words reads like a list of statements. The number worth watching is not the average but how many sentences run past 25 words.
Can I check the readability of HTML?
Yes. Paste the markup and the tags are stripped before scoring. Block elements such as headings, list items and paragraphs become line breaks rather than spaces, so a heading is never joined to the paragraph under it and counted as one long sentence.
Does readability matter for AI search and LLM citations?
Indirectly, and for the same reason it matters to people. A model lifting an answer needs a sentence that stands on its own. Long, hedged, clause-heavy sentences are harder to quote without losing the meaning, so they get quoted less.
Should every page target the same reading level?
No. A pricing page and an API reference have different readers with different tolerance for jargon. Score them against their own audience, and treat a jump in grade level between drafts as more informative than the absolute number.
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