Readability Scores Explained: Flesch, Grade Level, and How to Hit Your Target

A readability score is a number that estimates how hard a piece of text is to read, calculated from things a computer can count: sentence length, word length, syllables per word. It does not know whether your argument is clear or your facts are right. But it is a reliable early warning that a paragraph is going to lose people, and because it is a formula, it gives writers and editors a shared, arguable target instead of “this feels dense”.

This guide explains the four scores you will see most often, the ranges that suit different audiences, and the specific edits that change the number.

The four common formulas

Flesch Reading Ease

Scored 0–100; higher is easier. The formula penalises long sentences and long words:

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206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words)

Score	Reads like	Typical audience
90–100	Very easy	Children’s books, simple instructions
70–80	Fairly easy	Consumer marketing, most blog posts
60–70	Standard	News, general non-fiction
50–60	Fairly difficult	Trade publications, B2B content
30–50	Difficult	Academic writing, legal text
0–30	Very difficult	Scientific papers, contracts

Flesch-Kincaid Grade Level

The same inputs, rescaled to a US school grade. A score of 8.0 means an average eighth-grader (age 13–14) can follow it. Most guidance for public-facing writing lands between grade 7 and 9. Government plain-language standards in the US and UK aim at grade 8 or below.

Gunning Fog Index

Also produces a grade level, but counts “complex words” (three or more syllables, excluding proper nouns and common suffixes) instead of total syllables. It is harsher on jargon-heavy text than Flesch-Kincaid, which makes it useful for technical and financial writing where the problem is vocabulary rather than sentence length.

SMOG

Estimates the years of education needed to understand the text, based on polysyllabic words in a 30-sentence sample. Health-literacy researchers prefer it because it targets full comprehension rather than partial understanding, so it tends to run one to two grades higher than Flesch-Kincaid on the same text.

The Free Readability Checker calculates all four at once, plus average sentence length and the percentage of complex words, so you can see which input is dragging the score.

What score should you aim for?

There is no universal target, only a match between text and reader:

• Landing pages, product descriptions, email: Flesch 65–80, grade 6–8. People skim these on phones.
• Blog posts and how-to content: Flesch 55–70, grade 7–9. Explanations need some longer sentences.
• B2B and technical documentation: Flesch 45–60, grade 9–12. Jargon is appropriate when the reader shares it; do not dumb down terms your audience uses daily.
• Legal, medical patient information, public-sector: aim for grade 6–8 regardless of subject. These readers are often stressed, and comprehension has consequences.

Two cautions. First, the formulas were designed for English; on other languages the absolute numbers mean little, though relative comparisons between drafts still work. Second, a high score is not automatically good. Text can hit grade 5 by being choppy and repetitive. Use the score to find problems, not as a goal in itself.

Five edits that move the score fastest

1. Split sentences over 25 words. Average sentence length is the biggest lever in every formula. Look for “and”, “which” and semicolons as split points.
2. Replace three-syllable words with one- or two-syllable equivalents. Utilise → use. Approximately → about. Implement → do, set up, add. Keep technical terms that carry meaning; cut the ones that are just longer.
3. Turn nominalisations back into verbs. “We made a decision to” → “we decided”. “Conduct an evaluation of” → “evaluate”. This shortens the sentence and the words at once.
4. Break up paragraphs. The formulas ignore paragraph length, but readers don’t, and a wall of text is the most common reason a page with a good score still feels hard.
5. Move the point to the front. Sentences that start with a long dependent clause (“Although the majority of respondents who completed the survey indicated that…”) force the reader to hold the whole thing in memory. Lead with the subject and verb.

A worked example

Before (Flesch 34, grade 14):

In consideration of the fact that the implementation of the aforementioned optimisation methodology necessitates the allocation of significant engineering resources, it is recommended that stakeholders undertake a comprehensive evaluation of anticipated benefits prior to commencement.

After (Flesch 68, grade 7):

This optimisation will take a lot of engineering time. Before starting, stakeholders should check whether the expected benefits justify it.

Same meaning, 41 words down to 21, and a reader can act on it without re-reading.

Readability and search rankings

Google has said readability scores are not a ranking factor. What does affect rankings is whether people stay on the page and find what they came for, and easier text keeps more of them. Treat readability as a user metric that happens to help SEO indirectly, not a box to tick. If you are also checking keyword placement, the Keyword Density Checker and Character Counter cover the other on-page numbers editors usually want alongside a readability score.

Frequently asked questions

What is a good Flesch Reading Ease score?

60–70 suits general audiences. Marketing copy often aims higher (70–80); technical writing for experts can sit lower (45–60) without harm.

Why do different tools give different scores for the same text?

Syllable counting is done by algorithm and tools disagree on edge cases (hyphenated words, numbers, abbreviations). Differences of a few points are normal; compare drafts within one tool.

Should I write at a lower grade than my readers?

Usually one or two grades lower. Even highly educated readers prefer simpler text when they are skimming, tired, or on a phone, which is most of the time.

Do headings and bullet points count?

Most tools treat each heading or bullet as a short sentence, which lowers the average and inflates the score slightly. Check the body paragraphs on their own if the page is list-heavy.