Writing Clearly: Readability Scores, Plain Language, and Tools That Help
Learn how readability scores work, what the Flesch-Kincaid and Gunning Fog indices actually measure, and how to write clearer content that reaches more readers.
Most professionals write harder than they need to. Long sentences, abstract vocabulary, and dense paragraphs make readers work — and most readers will stop working and move on. Readability isn't about dumbing down your content. It's about respecting your reader's time and attention.
What readability scores actually measure
Readability formulas were developed in the mid-20th century to assess reading difficulty without human review. They use two primary factors that correlate strongly with difficulty:
- Sentence length — longer sentences are harder to parse
- Word complexity — longer words (more syllables) are harder to recognize and process
That's it. These are proxies for true readability, not direct measurements. A text about nuclear physics written at Grade 6 level is still about nuclear physics. But within a domain, these scores reliably differentiate clear writing from murky writing.
The major readability indices
Flesch Reading Ease (0–100)
FRE = 206.835 − (1.015 × avg sentence length) − (84.6 × avg syllables per word)
| Score | Reading ease | Target audience |
|---|---|---|
| 90–100 | Very easy | 5th grade |
| 70–80 | Easy | 6th–7th grade |
| 60–70 | Standard | 8th–9th grade |
| 50–60 | Fairly difficult | 10th–12th grade |
| 30–50 | Difficult | College level |
| 0–30 | Very difficult | Professional/academic |
Target for most web content: 60–70 (standard).
Flesch-Kincaid Grade Level
FKGL = (0.39 × avg sentence length) + (11.8 × avg syllables per word) − 15.59
Returns a US school grade level. A score of 8.3 means a typical 8th grader can understand it. Most popular news websites target Grade 8–10.
Gunning Fog Index
Fog = 0.4 × (avg sentence length + % of "complex" words)
"Complex words" = words with 3+ syllables (excluding proper nouns, compound words, and common suffixes like -ing, -ed).
Fog Index directly in school grade years. Target: below 12 for general audiences; below 10 for broad consumer content.
SMOG Index
More aggressive than Flesch-Kincaid — counts polysyllabic words more strictly. Often used in healthcare writing, where misunderstanding is dangerous. Target: Grade 6–8 for patient-facing health content.
ARI (Automated Readability Index)
Uses character count instead of syllables — easier to compute programmatically, similar results. Often used in automated content pipelines.
Check all these scores simultaneously with our Readability Score Checker — paste your text and get all major indices, plus sentence and word complexity breakdowns.
What these scores don't measure
- Organization and structure — a well-scored but poorly organized article is still hard to follow
- Accuracy — simplified text can be misleading
- Tone — cold, bureaucratic writing can score fine on Flesch but alienate readers
- Jargon — domain-specific short words (e.g., "PCR", "API", "NDA") count as simple but may confuse general audiences
- Visual design — small font, low contrast, and wall-of-text layout defeat even perfectly scored copy
Readability scores are a useful signal, not the final word.
Practical techniques to improve readability
1. Shorten sentences
The single most effective change. Split compound sentences at the conjunction:
❌ The system processes requests asynchronously, which means that when a
user submits a form, the server queues the job and immediately returns
a response, while the background worker picks up the task and notifies
the user via email when complete.
✅ The system processes requests asynchronously. When a user submits a
form, the server queues the job and returns immediately. A background
worker then picks up the task. The user receives an email notification
when it's complete.
Target: average sentence length of 15–20 words.
2. Prefer shorter words
Use the simpler word when both are accurate:
| Complex | Simpler |
|---|---|
| Utilize | Use |
| Commence | Start |
| Terminate | End |
| Subsequently | Then |
| In the event that | If |
| In order to | To |
| At this point in time | Now |
| Due to the fact that | Because |
3. Use active voice
Active voice shortens sentences and makes the subject of the action clear:
❌ Passive: The report was submitted by the team on Friday.
✅ Active: The team submitted the report on Friday.
❌ Passive: Errors are detected by the system and logged automatically.
✅ Active: The system detects errors and logs them automatically.
Use our Find & Replace with regex to find passive voice patterns: search for \b(is|are|was|were|be|been|being)\s+\w+ed\b.
4. Break up dense paragraphs
Long paragraphs are visually intimidating. One idea per paragraph. Three to four sentences is usually enough.
5. Use concrete, specific language
Abstract language forces readers to build their own mental model — which takes more effort:
❌ Abstract: The tool significantly improves performance.
✅ Concrete: The tool reduces page load time from 4.2s to 1.1s.
❌ Abstract: We offer comprehensive support.
✅ Concrete: We respond to support tickets within 4 business hours.
6. Front-load key information
Readers often skim. Put the most important information first in paragraphs and articles — don't build to a conclusion if your reader might not reach the end.
7. Use lists for steps and options
Numbered lists and bullet points are far easier to scan than prose:
❌ You need to first install Node.js, then clone the repository, then run
npm install to install dependencies, and finally run npm start.
✅ 1. Install Node.js
2. Clone the repository
3. Run: npm install
4. Run: npm start
Checking word count and metrics
Before publishing, get the stats on your content:
- Word count: Use our Word Counter to check character count, words, sentences, paragraphs, and estimated reading time.
- Readability: Run through Readability Score for all major indices.
- Grammar: Use AI Grammar Checker to catch errors that affect readability — run-ons, unclear pronoun references, and punctuation issues.
When AI-written text needs humanizing
AI-generated content often scores well on readability formulas but feels robotic — repetitive sentence structure, overuse of transitional phrases ("Furthermore," "It is important to note that"), and a characteristic flatness.
Use our AI Text Humanizer to rewrite AI-generated text to sound natural and conversational while preserving the original meaning.
Target readability by content type
| Content type | Target Flesch-Kincaid Grade | Notes |
|---|---|---|
| Consumer product pages | 6–8 | Clear, scannable |
| Blog posts | 8–10 | Accessible to broad audiences |
| News articles | 8–10 | AP Style Guide target |
| Business reports | 10–12 | Professional but not academic |
| Legal documents | 12–16 | Precision over accessibility |
| Academic papers | 14–18 | Discipline-specific expectations |
| Medical patient info | 6–8 | Health literacy research shows lower is safer |
A Grade 8 target doesn't mean your content is unsophisticated — it means your ideas are clearly expressed.
Readability as respect
Clear writing isn't simple thinking. It's the result of understanding your material deeply enough to explain it simply. The extra effort you spend making your writing easy to read is time you give back to every reader who encounters it. At scale, that compounds enormously.