A professor once returned my essay with a single comment: "Reads like you swallowed a thesaurus." He was right, and the wound taught me the most counterintuitive lesson in writing: sounding smart and being understood are opposite skills. Readability scores exist to measure the second one. They reduce your prose to sentence length and word length, crank through 70-year-old formulas, and tell you which school grade can follow along. Here is what the three big scores mean, what to aim for, and why short sentences beat fancy words every time.
Flesch Reading Ease: The 0–100 Thermometer
Developed by Rudolf Flesch in 1948, Reading Ease scores 90+ for comics-simple text, 60–70 for plain English that most adults read comfortably, and below 30 for academic treacle. The math rewards short sentences and short words — nothing else. Most successful blogs, news sites, and product pages cluster at 60–70, which reads as "effortless" without insulting anyone's intelligence. If your draft scores 40, do not reach for simpler synonyms first; split sentences first. One 35-word sentence cut in two routinely gains 10+ points alone.
Flesch-Kincaid Grade: The Number Clients Understand
Same inputs, different packaging: Grade Level translates to US school grades, so "Grade 8" means an eighth-grader can parse it. This is the score that appears in contracts and content briefs ("write at Grade 8 or below"), because non-writers grasp grades instantly. Target Grade 7–9 for general audiences, Grade 10–12 for trade publications, and whatever the subject demands for specialist docs — a quantum computing paper at Grade 16 is not failing, it is accurately labeled.
Gunning Fog: The Jargon Detector
Robert Gunning's index adds a penalty for "complex" words (3+ syllables), estimating years of schooling needed. It is the score that catches corporate fog — utilize, facilitate, operationalize — because polysyllabic filler inflates it fast. Run a buzzword-heavy paragraph through it, watch Fog hit 18, then replace five words and watch it drop to 11. Genuinely useful as a pompousness alarm.
Readability FAQs
Why do scores differ between tools?
Syllable counting is heuristic everywhere — no checker parses a real dictionary per word. Expect a point or two of wobble between Word, Yoast, and ours. Bands and trends agree; decimals are decoration.
My academic paper scores Grade 16. Is that bad?
Not necessarily. Scores describe, they do not judge. A paper for specialists should score high. The failure mode is a Grade-16 help article — difficulty your audience never signed up for.
Can short text be scored reliably?
Below ~100 words, one long sentence swings everything — treat small-sample scores as hints. Paste 200+ words for numbers you can steer by.
Paste your draft and get all three scores in one click.
Score My Writing Free