Readability Score Calculator

Flesch Reading Ease (FRE)

Developed by Rudolf Flesch in 1948, this formula scores text on a 0–100 scale. Higher scores mean easier reading. The formula is: 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words). A score of 60–70 is considered standard — easily understood by 13–15 year old students. Most web content should aim for 60 or above.

Flesch-Kincaid Grade Level

Created by J. Peter Kincaid for the US Navy, this formula converts readability into a US grade level. The formula is: 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59. A result of 8.0 means the text is suitable for an eighth-grader (13–14 years old). For general web content, aim for grade 7–9.

Gunning Fog Index

Developed by Robert Gunning in 1952, this index estimates the years of formal education needed to understand a text on first reading. The formula is: 0.4 × ((words ÷ sentences) + 100 × (complex words ÷ words)). “Complex words” are those with three or more syllables, excluding common suffixes like -es, -ed, and -ing. A Fog Index of 12 requires roughly a high-school senior reading level. For most audiences, aim for 8–12.

Tips for Better Readability

• Keep sentences under 20 words on average.
• Use common, everyday words instead of jargon or technical terms.
• Break long paragraphs into shorter ones.
• Use active voice instead of passive voice.
• Front-load your main point in each paragraph.
• Read your content aloud — if you stumble, simplify.