Text Readability Score Calculator

How to use the readability calculator

1. Paste your text

Drop a paragraph, an essay, an article draft, or any block of text into the input box. The calculator works on a single sentence (with low confidence) up to multi-page documents.

2. Read the six scores

Each formula gives a slightly different readability estimate. Compare them: if all six agree on a grade level, that is a reliable target. If they disagree (Flesch says grade 6 but Gunning Fog says grade 12), the text probably has unusual sentence-length-to-word-length ratios.

3. Adjust and recompute

Edit the text directly in the input box; the scores recompute live as you type. Try shortening sentences, swapping long words for short ones, or breaking paragraphs to see how each change affects the scores.

4. Copy the scorecard

Click Copy scores to grab a text-only version of the score card for pasting into a document or email. See also: Word Counter.

What each formula measures

Flesch Reading Ease (0-100)

Higher is easier. 90-100: 5th grade reading level. 60-70: plain English, typical news writing. 30-50: college level. Below 30: graduate-school dense. Calculated from average sentence length and average syllables per word.

Flesch-Kincaid Grade Level

U.S. school grade. Same inputs as Flesch Reading Ease but expressed as a grade number. Grade 8 means an average 8th grader can understand. Common targets: marketing copy at grade 5-7, news at grade 6-8, business writing at grade 10-12.

Gunning Fog Index

Years of formal education needed. Uses average sentence length plus percentage of complex words (3+ syllables). Heavier penalty for jargon than Flesch.

Automated Readability Index (ARI)

Grade level from character count and sentence length. Skips syllables; useful when syllable estimation is unreliable (technical text, proper nouns).

SMOG Index

Grade level focused on polysyllabic words. Often higher than Flesch-Kincaid for the same text. Common in healthcare-document readability requirements.

Coleman-Liau Index

Grade level from character count and sentence count. Like ARI, no syllable estimation. Useful for content that mixes English with code or symbols.

How to improve a readability score

If your draft scores higher than your target audience reads, three levers move the score most:

Shorten sentences

Sentence length is the dominant input to every formula. A 40-word sentence almost guarantees a grade-12+ score. Cut sentences in half. Look for the sentence with the most commas; that is usually the candidate for splitting.

Swap long words for short ones

Polysyllabic words (utilization, demonstrate, facilitate) trigger Gunning Fog and SMOG. Replace with use, show, help. Plain Anglo-Saxon usually scores better than Latin-derived synonyms.

Break paragraphs

Paragraph length is not in the formulas directly, but a wall of text is read as denser even with the same per-sentence stats. Break every 3-5 sentences for body copy, every 2-3 for marketing.

When formulas disagree

The six formulas weight inputs differently. Disagreement is informative.

High Flesch ease, high Gunning Fog

Short sentences but lots of polysyllabic words. Typical pattern: jargon-dense business prose. Switch the jargon to plain language and both scores converge.

Low Flesch ease, low Coleman-Liau

Long sentences with simple words. Typical of narrative or stream-of-consciousness prose. Both readers and formulas struggle with sentence length, even when individual words are easy.

High ARI, low SMOG

Long words but few of them are 3-syllable. Typical when a few technical terms dominate the text. SMOG misses them; ARI catches them via character count.

For most use cases, the average of the four grade-level scores (Flesch-Kincaid, Gunning Fog, ARI, SMOG) is a reasonable summary. Use Flesch Reading Ease as a quick directional check; use the others to pinpoint why your draft is hard to read.

Target grade by content type

Different audiences expect different reading levels. Common targets:

If your audience is broad (consumer marketing, public communication, healthcare for general public), aim for grade 6-8. If your audience is specialized (engineers, lawyers, doctors), grade 11+ is fine.

Limits and caveats of readability scores

Readability formulas are crude. A few real limits:

They do not measure comprehension

A short sentence with simple words can be confusing if the concept is unfamiliar. The formula gives the same low score to a clear explanation and to a vague hand-wave that uses the same vocabulary.

They penalize technical terms uniformly

"Cardiovascular" gets the same penalty in a medical journal as in a children's book. In context, the journal reader knows the word; the child does not. Adjust the target grade to the audience, not to a universal number.

They reward fragments

You can game the score by writing in fragments. The formulas think your text is easier. Real readers think it is harder to follow.

They are English-centric

All six formulas were built on English text. They give unreliable scores for translated content, multilingual text, or non-English writing.