Readability Scores

about this tool

Four scores, all built from the same three counts: how many words, how many sentences, and how many syllables. Paste a draft and you get the numbers, what they mean in words, and the sentences dragging them down.

The two levers

Every formula on this page is a ratio of words per sentence and syllables per word. That is the whole mechanism, and it is worth knowing because it tells you what to change.

A score that will not improve however you simplify the vocabulary is telling you the sentences are too long. A score that stays low after you split every sentence is telling you the words are.

What each one is for

Flesch Reading Ease is the one people quote, and the only one where higher is easier. 60 to 70 is plain English; below 30 reads like a contract.

Flesch–Kincaid Grade answers the same question as a US school year, which is easier to act on than a number out of 100.

Gunning Fog leans harder on the proportion of long words, so it punishes jargon more than sentence length.

SMOG is the one medical and public-health writing tends to use. It was published as a formula over a sample of thirty sentences and is calibrated for that; shorter text is extrapolated here so the number still appears, and the page tells you when that has happened.

The syllable count is an estimate

English spelling does not record where the syllables are. Every tool that claims a syllable count is guessing with a set of rules — count the vowel groups, drop a silent final e, give back the one that -le steals — plus a list of the words those rules get wrong.

Different tools give different answers. "Business" is two syllables or three depending on whose heuristic you ask, and that one word moves a short document's score.

So: these are estimates. They are good for comparing two drafts of the same piece, and for finding the paragraph that ran away. They are not measurements, and a tool that presents them to two decimal places without saying so is selling a precision it does not have.

Hardest sentences first

The list at the bottom scores each sentence on its own and sorts the worst to the top. This is usually the useful part: a document with a poor overall score often has three sentences doing the damage, and they are easier to fix than a whole draft.

Nothing is uploaded

The text stays in your browser. That matters here more than on most pages — what gets pasted into a readability checker is usually unpublished, sometimes confidential, and often somebody else's.

For counting rather than scoring, the word & character counter does words, sentences and reading time, and text diff compares two drafts line by line once you have rewritten one.

questions

What is a good Flesch Reading Ease score?

Around 60 to 70 is plain English that most adults read comfortably, which is what newspapers and good documentation aim for. Below 30 reads like a legal document. Above 90 is a children’s book.

Why do the four scores disagree with each other?

They weigh the two levers differently. Flesch–Kincaid leans on syllables per word, Gunning Fog on the proportion of long words, and all of them on sentence length. A document where they disagree usually has a few very long sentences rather than hard vocabulary.

How accurate is the syllable count?

It is an estimate, and it has to be. English spelling does not record where the syllables are, so every tool guesses with rules plus a list of exceptions, and different tools give different answers for words like "business". Use the scores to compare two drafts of the same piece rather than as a measurement.

Why does SMOG need thirty sentences?

It was published as a formula over a sample of thirty sentences and is calibrated for that. Shorter text is extrapolated here so the number still appears, and the page says when that has happened rather than presenting it as the real thing.

Does my writing get uploaded?

No. The whole thing runs in your browser, which matters when the draft is unpublished, confidential or somebody else’s.