Readability Checker

Five formulas, one question

Every readability formula answers the same question with slightly different arithmetic: how much effort does this text demand? They all rely on two proxies, sentence length and word length, because long sentences carry more clauses to hold in memory and long words are usually rarer.

The grade-level formulas usually agree within a point or two. When they disagree, the cause is informative: Gunning Fog and SMOG punish long words specifically, Coleman–Liau counts letters instead of syllables (so it is unaffected by syllable-counting errors), and Flesch–Kincaid is the most sensitive to sentence length.

How syllables are counted

The tool estimates syllables from spelling: it counts vowel groups, drops silent endings such as -ed and -es, and applies a few fixes for endings like -ing and -io. English spelling is irregular, so individual words can be off by one, but across a paragraph the errors average out. Numbers and abbreviations count as one-syllable words.

Worked example

Take this sentence from a typical corporate page:

Our organisation is committed to facilitating comprehensive stakeholder engagement initiatives across multiple operational jurisdictions.

That is 14 words, about 45 syllables and 9 complex words. Flesch Reading Ease comes out negative (shown as 0, “very difficult”) and Gunning Fog is about 31, well beyond any school grade. Rewritten:

We want to hear from all the people we work with, in each region.

Fourteen words, 16 syllables, no complex words. Reading Ease is about 96 and the grade level is between 3 and 6 depending on the formula. Nothing was lost except the impression of importance.

What score to aim for

Two benchmarks worth knowing: most newspapers sit around grade 9–11, and the UK and US government plain-language guidelines target grade 8 or lower for anything the general public must read. If you write for readers whose first language is not English, aim a grade or two lower than you would otherwise; the effort of reading in a second language stacks on top of the text’s own difficulty.

Practical tips

• Split any sentence over 25 words. The longest sentence is shown under the statistics; start there.
• Swap long Latinate words for short ones: utilise → use, commence → start, approximately → about, in the event that → if.
• Watch the “complex words” percentage. Above 15% is heavy for general readers; technical terms you cannot avoid should be surrounded by short, plain sentences.
• Do not chase a score at the cost of meaning. Necessary jargon (photosynthesis, depreciation) is fine. Padding (in order to, at this point in time) is not.
• Check readability before you humanize or paraphrase. AI drafts often score at grade 12–14 because they favour abstract nouns; bringing the grade down to 8–9 does most of the work of making them sound natural.
• For exams such as IELTS or UPSC, clarity beats complexity. Examiners reward precise vocabulary, not long words; a grade 9–11 essay with varied sentence length reads as controlled, not simple.

Read next

• Humanizing AI Text for SEO: What Google Actually Rewards — Google's real stance on AI content, what E-E-A-T means for AI-assisted pages, why humanized text still needs expertise, and a publisher's checklist.
• Readability Scores Explained: Flesch, Flesch-Kincaid and Gunning Fog — The formulas behind Flesch Reading Ease, Flesch-Kincaid Grade and Gunning Fog, what scores mean for web, email and academic text, and how to improve them.
• How to Summarize Long Articles Fast (Without Losing the Point) — Extractive vs abstractive summarizing, how to check a summary for missing facts, bullets vs paragraphs, study-note workflows and coursework ethics.

Frequently asked questions