Readability Score Checker

How Readability Formulas Work

Readability formulas estimate how difficult a piece of text is to understand. They analyze measurable properties of writing — such as word length, sentence length, and syllable count — to produce a score that corresponds to a school grade level or a difficulty rating. These formulas were originally developed for educators, publishers, and government agencies to ensure documents could be understood by their intended audiences.

The Five Readability Scores Explained

The Flesch Reading Ease score is one of the oldest and most widely used readability metrics. It produces a score from 0 to 100, where higher scores mean easier reading. A score between 60 and 70 is considered ideal for general-audience writing. The formula considers average sentence length and average syllables per word.

The Flesch-Kincaid Grade Level converts the same underlying data into a U.S. school grade level. A score of 8.0 means the text is suitable for an eighth-grade student. Most widely read content on the web scores between grade 6 and grade 9.

The Gunning Fog Index focuses specifically on complex words — those with three or more syllables. It estimates the number of years of formal education a reader needs to understand the text on first reading. Business writing should generally aim for a Fog Index below 12.

The SMOG Index (Simple Measure of Gobbledygook) is considered one of the most accurate grade-level predictors, especially for healthcare and government documents. It estimates the years of education needed to understand a piece of writing based on the density of polysyllabic words.

The Coleman-Liau Index is unique because it relies on character counts rather than syllable counts. This makes it easier to compute programmatically and less susceptible to syllable-counting errors. It estimates the U.S. grade level needed to comprehend the text.

What Grade Level Should You Target?

The ideal grade level depends on your audience. For general web content, blog posts, and marketing copy, aim for a grade level between 6 and 9. This does not mean your readers are uneducated — it means your writing is clear, concise, and easy to scan. Even highly educated readers prefer simpler writing because it requires less cognitive effort. Major publications like The New York Times write at roughly a 10th-grade level, while the most popular online content is often at a 6th to 8th-grade level.

How to Improve Your Readability Score

• Shorten your sentences: Break long, compound sentences into two or three shorter ones. Aim for an average of 15 to 20 words per sentence.
• Use simpler words: Replace multi-syllable words with shorter alternatives when the meaning is the same. Use "help" instead of "facilitate," "use" instead of "utilize," and "start" instead of "commence."
• Write in active voice: Active sentences are shorter and more direct. "The team completed the project" is clearer than "The project was completed by the team."
• Break up paragraphs: Use short paragraphs of 2 to 4 sentences. White space makes text less intimidating and easier to scan on screens.
• Cut unnecessary words: Remove filler phrases like "in order to," "due to the fact that," and "it is important to note that." These inflate word count without adding meaning.
• Use lists and headers: Structured content with bulleted lists and clear headings improves scannability, even if the readability formula score stays the same.

Limitations of Readability Formulas

Readability scores are useful guidelines, but they have limitations. They measure surface-level text properties and cannot evaluate concept difficulty, prior knowledge requirements, or writing quality. A sentence full of short, simple words can still be confusing if the ideas are poorly organized. Conversely, well-structured text with some longer words can be very clear. Use these scores as one input among many when evaluating your writing, and always test with real readers when possible.