Readability Score Checker

What the readability Score Checker does

Readability formulas estimate how hard a text is to read from two measurements: how long the sentences are and how long the words are. That is genuinely all they do. They cannot judge whether your argument is clear, whether the structure makes sense, or whether the vocabulary suits your audience — but sentence length and word length correlate well enough with reading difficulty that the scores are useful as a rough gauge.

Five formulas are calculated here because they weight things differently. Flesch Reading Ease runs 0–100, higher being easier; 60–70 is plain English and is what most web style guides target. Flesch-Kincaid Grade converts the same inputs into a US school grade. Gunning Fog leans harder on words of three or more syllables. SMOG is built around polysyllabic words and is the formula most used in healthcare, where getting comprehension right matters most. Coleman-Liau counts characters rather than syllables, which makes it more reliable on text full of names and technical terms that syllable estimators mishandle.

The most useful part of this page is not the scores. It is the list of hardest sentences underneath. Every one of these formulas is dominated by sentence length, so splitting your five longest sentences will move all five scores at once — and unlike swapping words for shorter synonyms, it makes the writing genuinely better rather than merely shorter.

The passive-voice count is a rough heuristic based on a form of to be followed by a past participle. It catches most passives and produces some false positives. Passive voice is not wrong, but a high count in instructional writing usually signals sentences that could be more direct.

How to use it

1. Paste your text. HTML is fine — leave the strip-tags option ticked.
2. Read the Flesch score first; 60–70 suits a general audience and 50–60 a specialist one.
3. Work down the hardest-sentences list, splitting each one rather than simplifying its vocabulary.
4. Re-check. Splitting long sentences usually moves every score at once.

A worked example

One sentence, before and after:

Before (41 words, Flesch ~28):
The implementation of the aforementioned methodology, which was developed
subsequent to extensive consultation with stakeholders across multiple
departments, necessitates a fundamental reconsideration of existing
operational procedures.

After (24 words across two sentences, Flesch ~62):
We built this method after talking to teams across several departments.
Using it means rethinking how we currently work.

The score moved 34 points. Notice what actually changed: the sentence was split, and the nominalisations (implementation, reconsideration) became verbs. The vocabulary was not dumbed down — it was un-inflated. That is almost always where a bad readability score comes from.

Frequently asked questions