How to Check Your Writing's Reading Level

Your patient education brochure needs to be at a 6th-grade reading level per American Medical Association (AMA) guidelines — but you just checked and it scores at 11th grade. Every extra grade level you go above the target audience's reading ability costs you comprehension, compliance, and ultimately outcomes. Here's how to understand readability scores and bring your text down to where it needs to be.

The Four Major Readability Formulas Explained

No single formula is "correct" — each was developed for different purposes and uses different inputs. Understanding what each one measures helps you choose the right tool for your audience.

Flesch-Kincaid Grade Level

The most widely used formula, built into Microsoft Word's Spelling & Grammar checker and used by the US Department of Defense for training materials. It translates directly to a US school grade level.

Formula: 0.39 × (words/sentences) + 11.8 × (syllables/words) – 15.59

A score of 8.0 means an average 8th grader can read your text. The formula penalizes both long sentences and long words — two independent levers you can pull to lower your score.

When to use it: General-purpose content, website copy, business communication, journalism.

Flesch Reading Ease

The older sibling of Flesch-Kincaid, this formula produces a 0–100 score rather than a grade level. Higher scores mean easier reading. The scale:

• 90–100: Very easy (5th grade) — comic books, simple children's books
• 70–80: Easy (6th grade) — conversational writing, plain English
• 60–70: Standard (7th–8th grade) — most web content and news articles
• 30–50: Difficult (college level) — academic writing, professional documents
• 0–30: Very difficult (professional/graduate level) — legal and scientific texts

When to use it: When you want a single "ease" score rather than a grade level, or when targeting international audiences who may not understand US grade levels.

Gunning Fog Index

Created by Robert Gunning in 1952 to measure the readability of newspapers. It focuses specifically on complex words — defined as words with three or more syllables.

Formula: 0.4 × [(words/sentences) + 100 × (complex words/words)]

A Fog Index of 12 means 12 years of formal education are needed to understand the text on first reading. The New York Times typically scores around 11–12. Time Magazine targets 10. A Fog Index above 18 is considered unreadable for most general audiences.

When to use it: Journalism, marketing copy, annual reports — anywhere you want to avoid corporate jargon and complex vocabulary.

SMOG Index (Simple Measure of Gobbledygook)

Developed by G. Harry McLaughlin in 1969 specifically for healthcare and patient education materials. Research consistently shows SMOG is the most accurate predictor of reading comprehension for health content.

Formula: 3 + √(polysyllabic word count in 30 sentences)

Unlike Flesch-Kincaid, SMOG accounts for 100% reading comprehension rather than average comprehension — meaning the grade level it outputs represents what a reader needs to fully understand, not just get the gist of.

When to use it: Patient education, public health materials, health literacy assessments. The AMA and CDC recommend SMOG for all health communication.

Target Reading Levels by Audience

Match your writing level to your audience's ability and purpose. When in doubt, write simpler than you think necessary — most readers will not notice that content is easy, but they will notice when it's difficult.

Note that legal documents intentionally score at a high grade level — precision matters more than accessibility in legal drafting. Healthcare is the opposite: lives depend on patients understanding instructions, so the AMA mandates a 5th–6th grade target.

How to Lower Your Reading Level

If your text scores too high, these techniques reliably move the needle:

Replace long words with short ones. The fastest lever. "Utilize" → "use." "Facilitate" → "help." "Demonstrate" → "show." "Approximately" → "about." "Implement" → "do." Every three-syllable word replaced with a one-syllable word improves every readability formula simultaneously.

Break compound sentences into shorter ones. "The patient should take the medication twice daily with food, and if they experience nausea, they should contact their doctor" becomes two sentences: "Take this medication twice daily with food. Call your doctor if you feel nauseous." Shorter sentences dramatically improve Flesch-Kincaid scores.

Use active voice. "The form must be completed by the patient" → "Complete the form." Active voice typically produces shorter, more direct sentences with fewer syllables per phrase.

Cut jargon and explain necessary technical terms. If you must use "hypertension," follow it immediately with "(high blood pressure)." Don't assume prior knowledge — define terms the first time you use them.

Use bullet points for lists. A sentence listing four items with "and" creates a long sentence that scores high on readability formulas. Breaking it into four bullets dramatically reduces sentence length metrics.

Worked Example: Before and After

Consider this original paragraph from a healthcare brochure (SMOG Index: 14.2, Flesch-Kincaid Grade Level: 13.8):

"Hypertension, frequently characterized as the 'silent killer' due to its asymptomatic presentation in the majority of cases, necessitates consistent monitoring of sanguineous pressure readings to facilitate appropriate pharmacological intervention prior to the manifestation of cardiovascular complications."

Revised version (SMOG Index: 6.1, Flesch-Kincaid Grade Level: 5.9):

"High blood pressure often has no symptoms. That's why doctors call it the 'silent killer.' Check your blood pressure regularly. Early treatment stops heart problems before they start."

Both convey the same information. The revision uses shorter words, shorter sentences, and active constructions — and the SMOG score dropped by 8 grade levels.

Reading Level and SEO

Google's ranking algorithms consider content quality signals, including whether your text appropriately matches the complexity of the query. Informational queries ("how to lower blood pressure") come from people expecting plain-English explanations, not medical journal abstracts.

Pages that match reading level to search intent tend to have lower bounce rates and higher time-on-page — both positive engagement signals. A patient education page written at a 13th-grade level for a 6th-grade audience will see users leave quickly, unable to understand the content.

For web content targeting the general public, aim for 6th–8th grade (Flesch-Kincaid) or a Flesch Reading Ease score of 60–70. For specialized audiences — developers, doctors, attorneys — a higher grade level is appropriate and expected. Use the Reading Level Analyzer to check your text against all five major formulas simultaneously and see a per-sentence difficulty breakdown.