Free readability checker with your Flesch Reading Ease score & grade level

A readability checker scores how easy your writing is to understand, turning fuzzy “this feels hard to read” feedback into a number you can act on. This readability checker computes the Flesch Reading Ease score and the Flesch-Kincaid Grade Level the moment you paste text, alongside the raw counts that drive them — words, sentences, syllables, average words per sentence and average syllables per word. Everything below explains what those numbers mean, what a good readability score actually is, why readability matters for SEO and conversions, and exactly how to raise your score without dumbing your writing down.

What is readability, and why measure it?

Readability is how much effort a reader has to spend to understand your text. Two things make writing harder: long sentences, which strain working memory, and long words, which are usually rarer and more abstract. Every mainstream readability test is built on those two signals. They cannot judge whether your argument is good or your facts are right, but they are remarkably reliable at predicting whether an average reader will glide through a passage or stall on it.

Measuring readability matters because writers are the worst judges of their own clarity. You already know what you meant, so dense prose reads fine to you. A text readability score is an outside opinion that does not share your assumptions. It is the same reason a spell-checker beats re-reading: the tool does not get tired, and it does not fill in the gaps your brain fills in automatically.

Flesch Reading Ease: the headline score

The Flesch Reading Ease score, developed by Rudolf Flesch in 1948, is the most widely used readability formula in the world — it is built into Microsoft Word, Google Docs add-ons and countless SEO plugins. It returns a number on a 0–100 scale where higher means easier. The formula is:

206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words)

In plain terms: start at 206.835, subtract a penalty for long sentences, then subtract a much larger penalty for long words. Shorten either and the score climbs. Here is how the bands break down and who each range suits:

What is a good readability score?

For most websites, blogs and marketing copy, a good Flesch Reading Ease score is 60–70 — the “standard” band that reads at an 8th-to-9th-grade level. That is not a comment on your readers’ intelligence; it is about cognitive load. Even expert readers prefer easy prose when they are skimming on a phone between meetings. The average American reads at roughly a 7th-to-8th-grade level, and major publications like the New York Times deliberately write around grade 8–10 to stay broadly accessible.

Context still matters. A pediatric health leaflet should aim higher (easier), around 70–80, because comprehension is safety-critical and the audience is wide. A whitepaper for data engineers can sit at 40–50 without a problem, because the readers are specialists who expect dense, precise language. The mistake is writing difficult prose for a general audience — that is where readers bounce. Use the score to confirm your writing matches who you are writing for.

Flesch-Kincaid Grade Level

The Flesch-Kincaid Grade Level uses the same two inputs but reports a US school grade instead of a 0–100 score. It was commissioned by the US Navy in 1975 to grade the difficulty of technical manuals, and it is now the standard many institutions and style guides cite. The formula is:

0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59

A result of 8.0 means an average 8th grader (around age 13) can read the text; 12.0 means a high-school senior; 16.0 is a college graduate. Reading Ease and Grade Level move in opposite directions — a higher Reading Ease pairs with a lower grade. Most teams track one or the other; both tell the same story. For web content, a Flesch-Kincaid grade of 6–9 is the comfortable target.

Other readability formulas worth knowing

Flesch is the most common, but it is not the only readability test. Each formula weights sentence length and word difficulty slightly differently, and knowing the alternatives helps you interpret any reading level checker you meet:

• Gunning Fog Index: estimates the years of formal education needed, based on sentence length and the share of “complex” words (three or more syllables). A Fog of 8–10 is ideal for a wide audience; above 12 gets hard.
• SMOG Index: “Simple Measure of Gobbledygook” predicts the grade needed for full comprehension and is especially popular for health and medical content, where it is considered conservative and reliable.
• Coleman-Liau Index: uses characters per word instead of syllables, which makes it easier for software to compute accurately since it never has to guess syllable counts.
• Automated Readability Index (ARI): like Coleman-Liau, it relies on characters rather than syllables and outputs a grade level.

They usually agree within a grade or two. Flesch Reading Ease remains the best default because it is universally understood and its 0–100 scale is intuitive. If you want a second opinion, run your text through a character-based formula like Coleman-Liau, which sidesteps syllable-counting error entirely.

How this tool calculates your score

To produce a readability score, the tool needs three counts: words, sentences and syllables. Words are runs of characters separated by whitespace. Sentences are detected by terminal punctuation — periods, question marks, exclamation points and ellipses. Syllables are the tricky one, because English spelling is irregular, so the tool uses a well-tested heuristic:

• Count the groups of consecutive vowels (a, e, i, o, u and sometimes y) — each group is roughly one syllable.
• Subtract a silent trailing “e” (as in “make” or “code”), which adds a letter but no sound.
• Never return fewer than one syllable per word, since every word has at least one.

This vowel-group method is accurate for the overwhelming majority of English words but can miss unusual cases (“queue”, “area”, silent-syllable loanwords). That tiny margin of error is why you should treat any readability score as accurate within a point or two of grade, not to the decimal. The number is a guide, not a verdict. Everything is computed on your device the instant you type, so you get a live reading with no round-trip to a server.

Why readability matters for SEO

Readability is not a direct Google ranking factor — there is no algorithm line that reads your Flesch score and bumps you up. But it drives almost every signal that is connected to ranking, which is why the question “does readability affect SEO?” gets a confident yes in practice:

• Dwell time and bounce: easy pages are finished, not abandoned. Longer, more engaged visits are a positive quality signal.
• Links and shares: people link to and share content they actually understood and enjoyed. Clear writing earns more of the authority links that do move rankings.
• Featured snippets and AI answers: Google’s snippets and AI Overviews, plus ChatGPT and Perplexity, favour clear, self-contained sentences they can lift and quote. Dense prose is harder to extract.
• Crawl comprehension: simpler sentence structures are easier for search engines to parse and associate with a topic.

In short, readability is an amplifier. A thorough page that is also easy to read out-performs an equally thorough page that is a slog. Pair readability with a solid word count — check length with the word counter — and sensible keyword placement, which you can audit with the keyword density checker.

Why readability matters for conversions

Before a reader can click your call to action, they have to understand your offer. Every extra moment of effort your copy demands is a moment they might leave instead. Studies of landing pages repeatedly find that simpler language lifts conversion rates, because confidence and comprehension go together — a visitor who easily grasps the benefit is far more likely to act on it.

This is sharpest in high-stakes moments: pricing pages, checkout copy, form instructions and error messages. If a reader has to re-read your refund policy twice, trust drops. Running your most important conversion copy through a readability checker and pulling it into the 60–70 range is one of the cheapest optimisation wins available — no redesign, no new traffic, just clearer words.

How to improve your readability score

Improving readability means lowering one of two numbers: average words per sentence or average syllables per word. Both are shown live in the tool above, so you can watch your score respond as you edit. Here is the practical playbook:

Shorten your sentences

The single biggest lever. Aim for an average of 15–20 words per sentence, with a mix of short and medium lengths for rhythm. Whenever a sentence runs past about 25 words, look for a conjunction (“and”, “but”, “which”) and split it into two. A full stop is the most powerful readability tool you own.

Use shorter, simpler words

Swap multisyllabic words for everyday ones: “use” for “utilize”, “help” for “facilitate”, “about” for “approximately”, “show” for “demonstrate”. Each swap cuts syllables per word, which the Flesch formula rewards heavily (the syllable term carries far more weight than the sentence term).

Prefer the active voice

“The team shipped the feature” beats “the feature was shipped by the team.” Active voice is shorter, more direct and easier to follow. It also tends to cut the little connecting words that pad sentence length.

Format for the eye, not just the formula

Short paragraphs (two to four sentences), descriptive subheadings, bullet lists and bold key phrases do not change the Flesch number much, but they transform perceived readability on a screen. A reader who can scan and find their answer feels the page is easy, and that feeling drives the engagement metrics SEO cares about.

What reading level should you write for?

The honest answer is: write for the reader who is tired, distracted and in a hurry — which is almost everyone, almost all the time. For general web content, target a 7th-to-9th-grade reading level (Flesch Reading Ease 60–70). Go easier for consumer health, government and safety information, where a grade 5–7 target makes sure no one is left behind. Reserve college-and-above difficulty for genuinely specialist audiences who expect it.

Writing simply is not the same as writing simplistically. You can explain a complex idea — quantum computing, tax law, machine learning — at a grade-8 reading level without losing any accuracy. The complexity lives in the ideas, not in the sentence structure. The best technical writers are masters of exactly this: hard concepts, easy sentences.

Readability checker vs Hemingway, Yoast and Grammarly

You may have seen readability feedback inside other tools. The Hemingway Editor highlights hard-to-read sentences and adverbs and shows a grade level; it is great for line-by-line editing but you paste into its own app. The Yoast SEO plugin runs a Flesch-based check inside WordPress as you write, flagging long sentences and passive voice with a traffic-light. Grammarly bundles a readability score alongside its grammar suggestions.

They are all built on the same underlying formulas this tool uses. The advantage of a dedicated, in-browser readability analyzer like this one is speed and privacy: no plugin to install, no account to create, no document uploaded to a server. Paste, read your score, edit, done — and your text never leaves your device. Use it as a fast first pass, then lean on the editing tools for sentence-level cleanup.

Privacy: why in-browser checking matters

This readability checker runs entirely in your browser with JavaScript. Nothing you type or paste is sent to a server, stored or logged — the calculation happens on your own device. That matters because writers routinely paste sensitive material into checkers: unpublished articles, client drafts under NDA, internal reports and pre-submission academic work. In-browser analysis removes the risk of that text being retained or exposed, so a privacy-respecting text readability tool is the safer default for anything confidential.

Treat your readability score as a compass, not a scoreboard. The goal is never to hit a magic number — it is to make sure the right reader can understand you with the least effort. Paste your text into the checker above, watch the Flesch Reading Ease and grade level update as you edit, and ship writing that more people actually finish.