Flesch Reading Ease Calculator
Scores how easy your writing is to read using the Flesch Reading Ease formula. Use it to check whether blog posts, legal documents, or educational materials match your target audience's reading level.
About this calculator
The Flesch Reading Ease formula was developed by Rudolf Flesch in 1948 and remains the most widely used readability metric in English. It evaluates two key variables: average sentence length (words per sentence) and average word length (syllables per word). Longer sentences and polysyllabic words both reduce readability. The core formula is: score = 206.835 − (1.015 × (totalWords / totalSentences)) − (84.6 × (totalSyllables / totalWords)). Scores range from 0 to 100 — scores of 60–70 are considered plain English suitable for general audiences, while scores below 30 indicate very difficult text (e.g., academic journals). This calculator also applies a textType multiplier so scores can be calibrated for different content categories such as technical documentation or creative writing.
How to use
Take a paragraph with 3 sentences, 60 words, and 90 syllables. Assume textType = 1.0 (standard prose). Step 1: Average sentence length = 60 / 3 = 20 words. Step 2: Average syllable count = 90 / 60 = 1.5 syllables per word. Step 3: Apply the formula — 206.835 − (1.015 × 20) − (84.6 × 1.5) = 206.835 − 20.3 − 126.9 = 59.635. Step 4: Multiply by textType (1.0) and round to one decimal: score = 59.6, which falls in the 'Standard' range — suitable for a general adult audience.
Frequently asked questions
What is a good Flesch Reading Ease score for different types of content?
Scores of 70–80 are ideal for consumer-facing content like blog posts and product descriptions — most adults can read them effortlessly. Educational materials and journalism typically target 60–70. Legal and financial documents often score 30–50, which is considered difficult. Academic or scientific writing frequently falls below 30, categorized as 'very difficult.' The right score depends on your audience: a children's book should score above 80, while a medical consent form might intentionally score lower due to required terminology.
How do syllables per word affect the Flesch readability formula?
The syllable component carries a large coefficient (84.6) in the Flesch formula, making it the dominant factor in most scores. Words with three or more syllables — called polysyllabic words — dramatically lower the score. For example, replacing 'utilization' (5 syllables) with 'use' (1 syllable) can measurably raise your score across an entire document. Writers aiming for plain English are advised to prefer shorter, common words wherever technical terminology is not required.
Why does sentence length matter for readability scores?
Longer sentences force readers to hold more information in working memory before they reach a full stop. This increases cognitive load and the chance of misunderstanding, especially for readers with lower literacy levels or those reading in a second language. The Flesch formula penalises sentence length with a coefficient of 1.015 per word above average. Splitting long sentences into two shorter ones almost always improves both the score and genuine comprehension, without changing the underlying meaning.