Readability Grade Checker
Check reading grade level using multiple formulas: Flesch-Kincaid, Gunning Fog, SMOG, Coleman-Liau. Free.
How to use
Four formulas, one verdict
Each formula weights different signals. Flesch-Kincaid uses sentence length and syllables. Gunning Fog penalises complex words (3+ syllables). SMOG (Simple Measure of Gobbledygook) was designed for medical text. Coleman-Liau uses character counts rather than syllables — easier for software to compute reliably. If three or more agree within 1 grade level, the result is solid. If they disagree by 3+ grade levels, the text has unusual patterns worth investigating.
Plain-language targets
UK government plain-language guidance targets grade 9 or below. US Plain Writing Act (2010) targets grade 8 or below for federal communications. Newspapers like The Sun and Daily Mirror sit around grade 7. Broadsheets like The Times and Guardian sit around grade 9-10. Academic journals sit around grade 14-18.
The Flesch-Kincaid Grade Level was developed for the US Navy in 1975 to assess training manuals. Plain-language laws in the US (Plain Writing Act 2010) require federal communications to score around grade 8 or below — most academic prose scores grade 12-16.
Different formulas weight different signals. Flesch-Kincaid looks at sentence length and syllables. Gunning Fog penalises 'hard' words (3+ syllables). SMOG was designed for medical text. If multiple scores agree, the result is reliable. If they disagree by 3+ grade levels, the text has unusual sentence/word patterns — usually worth investigating.
Frequently asked questions
Which readability formulas does the tool use?
Flesch-Kincaid, Gunning Fog, SMOG and Coleman-Liau. Each estimates the US school grade needed to understand the text using sentence length and word complexity.
What reading grade should I aim for?
For general public content, a grade 7-9 reading level (about age 12-14) is often recommended. Technical or academic writing can be higher.
Why do the formulas give different results?
Each uses different inputs, such as syllables, long words or letters per word, so scores vary slightly. Look at the overall range rather than a single number.