What readability score should you aim for?

Readability tools give you a number, and the natural next question is what the number should be. The honest answer is that it depends on who is reading and why. Still, editors and plain-language practitioners have settled on some working conventions, and they are a sensible place to start.

Common targets by audience

These are conventions, not rules. No formula or agency defines a single correct score, and the targets below are ranges that practitioners commonly use.

For reference, here is how Op-Ed Insight maps grades to school levels:

A grade score estimates the years of US schooling needed to understand the text on first reading. It is not a measure of quality.

A few notes on reading this table:

“General public” means everyone. That includes people reading in a second language, people with dyslexia, people who are tired, and experts outside their field. Plain-language practice often aims at about grade 8 or lower because clear text costs skilled readers nothing. A specialist reads a plain explanation faster, too.

Health information is commonly held to a lower target. Many health-literacy guides recommend writing patient materials at a sixth- to eighth-grade level. People reading about a diagnosis or a dose are often anxious, and a misunderstanding can hurt them. The SMOG index is often used for this kind of material.

Higher targets are a ceiling, not a goal. A research paper at grade 16 isn’t better than one at grade 13. Expert readers still prefer short sentences and plain verbs when the content allows.

US law sets no score. The Plain Writing Act of 2010 requires US federal agencies to write clearly for the public, but it names no formula or target. The Federal Plain Language Guidelines put the emphasis on knowing your audience, organizing for the reader, and testing. Some other rules do set scores. For example, some US states have used minimum Flesch Reading Ease scores for insurance policies. Check the rules that apply to your own field.

Why chasing a number backfires

A readability formula measures two proxies: sentence length and word length. If you treat the score as the goal, you will optimize the proxies instead of the clarity they stand for.

Take a notice from a utility company.

Before: Your account will be suspended if payment is not received by the due date. To avoid interruption of service, please ensure that your payment details are current.

27 words · 2 sentences · grade 7.6

Now push hard on the score and nothing else:

Pay now. Or we stop it. Do it by the date. Check your card.

That earns a very low grade, yet it is worse than the original. “Stop it” is vague (stop what?). “The date” is unexplained. The tone has turned curt. The score improved by deleting information and courtesy.

A rewrite aimed at the reader looks different:

After: Please pay by the due date on your bill. If we don’t receive your payment, we will turn off your service. Check that your card details are up to date.

30 words · 3 sentences · grade 1.7

It says who does what, names the consequence plainly, and keeps the polite tone. Its grade is lower than the Before, but the grade fell as a side effect of plain writing, not as the target.

Other ways score-chasing goes wrong:

• Splitting sentences mid-thought. Chopped sentences raise the score and break the logic that “because,” “although,” and “so” were carrying.
• Swapping precise words for vague ones. “Medication” becomes “stuff you take.” The score rises. Accuracy falls.
• Removing terms the reader needs. If readers will meet the word “deductible” on their insurance card, teach it. Don’t hide it.
• Ignoring structure. Headings, lists, and putting the main point first help more than a lower grade, and most formulas can’t see them.
• Reading too much into small samples. A two-sentence paragraph can score anywhere. Use at least a few paragraphs before you trust the number.

What to do instead

1. Picture one real reader. Someone specific from your audience, reading on the device and in the mood they’ll actually be in. Write for that person.
2. Put the main point first. Readers who stop early should still get it. See put the main point first.
3. Use plain words, and keep the precise ones. Swap “utilize” for “use” freely. Keep “deductible” and explain it. The plain words list helps with the first part.
4. Keep sentences short on average, not uniformly. A mix of short and medium sentences reads naturally. The sentence length checker flags sentences of 25 words or more for a second look.
5. Prefer active verbs. “We will turn off your service” beats “service will be suspended.” The passive voice finder shows likely candidates.
6. Then check the score. If it is well above your target, find out why. Usually a few long sentences or a cluster of abstract nouns are to blame. Fix those and stop.
7. Test when it matters. For forms, instructions, and health or legal material, ask a few people from your audience to read the text and tell you what it says. Their answers beat any formula.

The plain language principles guide covers the habits behind clear writing. Readability scores explained covers what the formulas can and can’t tell you.