Score English text with Flesch Reading Ease, Flesch-Kincaid grade, Gunning Fog and SMOG, plus average sentence length, word length and syllables.
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You type or paste your text and the tool analyzes it in real time. It breaks the text into sentences and words, counts the syllables in each word with a heuristic (vowel groups, with special handling for silent e and -le endings) and applies the four classic formulas. The cards show each metric and the difficulty level — all without sending anything to any server.
It is a 0–100 scale where higher means easier to read. The formula uses two ingredients: the average number of words per sentence (shorter is better) and the average number of syllables per word (fewer is better). A score above 90 typically reads as a sixth-grade level, while below 30 is college-level and dense.
A reader would need to be in roughly the 8th grade of the US school system to read the text with full comprehension. Grade 5–6 suits casual web copy, 7–9 is typical for most business documents, and 10+ signals technical or academic material.
Flesch scores every syllable, while Fog only counts 'complex' words — those with three or more syllables — on top of sentence length. That makes Fog a better fit for adult readers and jargon-heavy documents: adding one long technical word raises Fog noticeably but barely moves the Flesch score.
SMOG counts the words with three or more syllables per sentence and takes the square root. It was designed for medical and technical writing and is statistically most reliable when the text has about 50 sentences or more. For short snippets it is shown for reference, but Flesch and Fog are more stable there.
No. All four formulas and the syllable-counting heuristic were built for English, so scores for Spanish, Portuguese, Indonesian and other languages are unreliable. For other languages, look for readability formulas designed specifically for them.
If you just finished with Readability Calculator, the natural next steps are Word & Character Counter, Unique Word Counter, Duplicate Line Remover, or browse every tool in Daily Tools.