Which formula should I trust?

For most general writing, Flesch-Kincaid Grade Level is the most-cited. For health communications, SMOG is the standard. The "Average" combines all five for a balanced view.

Does the tool work for languages other than English?

No, these formulas are calibrated for English syllable patterns. Other languages need their own (e.g. Lix for Scandinavian languages).

How long does my text need to be?

At least 100 words for stable scores; 300+ for reliable ones. Below 100 words, sentence and word averages swing wildly with each addition.

What is Flesch Reading Ease?

A 0-100 score where higher = easier. 90-100 is 5th grade; 60-70 is plain English (8-9th grade); below 30 is graduate-level. The opposite direction from grade-level scores.

How is "complex word" defined?

A word with 3 or more syllables, excluding compounds, proper nouns, and common suffixes (-ed, -es). Used by Gunning Fog and SMOG.

How do I lower my readability score?

Three moves: (1) split long sentences, (2) replace 3+ syllable words with shorter synonyms ("utilize" → "use"), (3) cut filler ("in order to" → "to"). Each helps both grade level and Flesch reading ease.

Is grade level the same as years of education?

Yes, roughly. Grade 9 ≈ 9th grade in US (age 14-15) ≈ Year 10 UK ≈ Year 9 Australia. A grade-12 score means a typical high-school graduate can read it without difficulty.

Why do different formulas give different scores?

Each weights sentence length, word length, and syllable count differently. Flesch-Kincaid favours sentence length; SMOG favours complex words. The average smooths out individual quirks.

Can I trust this for academic submissions?

Yes for first-pass diagnostics. Don't use it as the only check, readability scores can't tell whether your argument is logical, your evidence is strong, or your structure works. Use our AI essay checker for content-level feedback.

Free Tool

Readability Score Calculator

Analyze your text with 6 different readability formulas including Flesch-Kincaid, Gunning Fog, SMOG, Coleman-Liau, and more.

Your Text

Enter Your Text

Paste or type text in the editor to see readability scores from 6 different formulas

Understanding Readability Formulas

Flesch-Kincaid

Based on sentence length and syllables per word. The most widely used formula, especially in education.

Gunning Fog

Estimates years of formal education needed. Focuses on complex words (3+ syllables) and sentence length.

SMOG Index

Designed for healthcare materials. Counts polysyllabic words to determine reading level.

Coleman-Liau

Uses characters per word instead of syllables. More reliable for machine-processed text.

Automated Readability

Uses character count and sentence length. Good for real-time text analysis.

Flesch Reading Ease

Scores 0-100 (higher = easier). The inverse of Flesch-Kincaid, focused on ease rather than grade.

Tips to Improve Readability

Shorter Sentences

Aim for 15-20 words per sentence. Break long sentences into smaller ones.

Simple Words

Use common words when possible. Replace "utilize" with "use", "commence" with "start".

Active Voice

Prefer "The team completed" over "It was completed by the team".

Break It Up

Use paragraphs, bullet points, and headings to organize content visually.

Flesch Reading Ease Score Guide

Score	Difficulty	Grade Level	Example
90-100	Very Easy	5th grade	Comics, children's books
80-89	Easy	6th grade	Consumer ads, tabloids
70-79	Fairly Easy	7th grade	Movie reviews, sports news
60-69	Standard	8-9th grade	Time, Newsweek
50-59	Fairly Difficult	High school	Wall Street Journal
30-49	Difficult	College	Academic papers
0-29	Very Difficult	Graduate	Scientific journals, legal docs

Want deeper writing analysis?

WriteScholar provides comprehensive AI feedback on grammar, structure, academic style, and more to help perfect your papers.

Free Readability Score Calculator, Flesch-Kincaid, Gunning Fog, SMOG

Paste your text to instantly see its readability across six leading formulas: Flesch-Kincaid Grade Level, Flesch Reading Ease, Gunning Fog Index, SMOG, Coleman-Liau, and Automated Readability Index. Get a single average grade level plus diagnostics on long sentences and complex words.

How to use it

Paste your text
Drop in any English passage of 100+ words. Shorter samples produce unreliable scores because formulas need enough sentence and word data to be meaningful.
Read the headline grade level
The "Average Grade Level" combines Flesch-Kincaid, Gunning Fog, SMOG, Coleman-Liau, and ARI. A score of 9 means roughly 9th-grade reading level, appropriate for general audiences.
Check the diagnostics
Below the scores, see your average words per sentence, syllables per word, percentage of complex (3+ syllable) words, and sentence count. These tell you what to actually fix.
Edit and re-score
Shortening sentences and replacing complex words is the fastest way to drop your grade level. Re-paste after editing to see the new score.

When you'd use this

Writing for a general audience (blog, news, marketing)

Aim for grade 6-8. Most popular blogs and news outlets target this range, readers skim, and complex prose loses them. Apple's marketing copy averages grade 4.

Writing for college students or professionals

Grade 10-12. Higher-ed audiences can handle longer sentences and three-syllable words, but cramming every sentence with jargon costs you readers.

Writing an academic paper

Grade 12-15 is normal for research papers. Some journals (Nature) explicitly target lower grade levels to broaden readership; others (specialist medical) accept higher.

Health, finance, or government communications

Plain-language laws in the US, UK, and Australia require grade 8 or below for public-facing health and government content. Score check is now standard practice.

Cleaning up an essay for clarity

If your readability score jumped 5 grade levels in one paragraph, you probably packed too much into one sentence. Split it.

Common mistakes to avoid

Targeting one specific score

Different formulas weight things differently. A passage can hit Flesch-Kincaid grade 8 but Gunning Fog grade 11 because they prioritize different features. Look at the average, not one number.

Lowering grade level by chopping random words

Cutting filler is good. Cutting precision to lower a number is bad. "Cardiopulmonary resuscitation" might raise your grade level, but "CPR" is fine if your audience knows the term.

Ignoring sentence length

Average words per sentence is the single biggest readability factor. Bringing it from 25 to 15 typically drops your grade level by 2-3.

Using readability for fiction

Readability scores are for non-fiction. Fiction breaks rules deliberately, Cormac McCarthy reads at college level by formula but is gripping. Don't score literary writing.

Forgetting your audience

Grade 6 for a peer-reviewed journal is too dumbed-down. Grade 14 for a kids' science magazine is too complex. Match the score to who's actually reading.

Examples

Lowering grade level via sentence splitting

Before

The committee recommended that all participating institutions submit comprehensive documentation regarding their compliance with federal accessibility standards by the end of the second quarter.

After

The committee made a recommendation. All institutions must submit accessibility documentation by Q2.

34 words → 16 words across 2 sentences. Grade level drops from ~17 to ~10. Same information, dramatically more readable.

Replacing complex words

Before

The methodology utilized in the experiment necessitated extensive preliminary calibration.

After

The method needed careful prep work first.

"Utilized" → "used"; "necessitated" → "needed"; "extensive preliminary calibration" → "careful prep work first". Drops average syllables per word and grade level.

Glossary

Flesch-Kincaid Grade Level: Most-cited readability formula. Outputs a US grade level (e.g. 9.5 = end of 9th grade). Heavily weights average sentence length.
Flesch Reading Ease: 0-100 score where higher = easier. 90-100: very easy. 60-70: plain English. Below 30: graduate-level. Inverse direction from grade level.
Gunning Fog Index: Years of formal education needed to understand text on first read. Weights complex (3+ syllable) words heavily.
SMOG Index: "Simple Measure Of Gobbledygook". Standard for health communications. Counts polysyllabic words in 30-sentence sample.
Coleman-Liau Index: Uses character count (not syllables) to estimate grade level. Useful for computer text analysis.
Plain Language: Writing that's clear and direct. Plain Writing Act of 2010 (US) requires federal agencies to write public materials at grade 8 or below.

Frequently asked questions

Depends on audience. For general blogs, grade 6-8. For business/professional, grade 10-12. For academic, grade 12-15. Below 6 reads as condescending; above 15 reads as inaccessible.