The Flesch-Kincaid formulas are two of the most widely used readability tests in English. They are simple enough to calculate by hand but useful enough to guide real writing decisions, and they are built into tools from Microsoft Word to Hemingway Editor.
Despite being referred to as a single test, there are actually two separate formulas, developed at different times for different purposes:
Both formulas use the same two inputs: average sentence length (ASL) and average syllables per word (ASW). Longer sentences and more complex words both make text harder to read.
Where ASL = words / sentences, and ASW = syllables / words.
Take this sample text:
"The quick brown fox jumps over the lazy dog. It was a fine day for running."
That is 18 words, 2 sentences, and approximately 22 syllables.
ASL = 18 / 2 = 9.0
ASW = 22 / 18 = 1.22
Short sentences with simple words produce high Reading Ease and low Grade Level, both good for general audiences. Try pasting that sample text into the scorer above to verify the calculation.
| Reading Ease | Difficulty | Typical Audience | Grade Level equiv. |
|---|---|---|---|
| 90-100 | Very easy | Children's content, age 11 | 5th grade |
| 70-90 | Easy | General consumer, everyday reading | 6th grade |
| 60-70 | Standard | Most web content, news | 7th-8th grade |
| 50-60 | Fairly difficult | Professional articles, some blogs | 10th-12th grade |
| 30-50 | Difficult | Academic papers, technical docs | College level |
| 0-30 | Very difficult | Legal, scientific, specialist texts | Professional |
Target for most websites: Aim for a Reading Ease of 60-70 and a Grade Level of 6-8. That balances clarity with credibility and is accessible to the widest online audience.
The two variables, sentence length and syllables per word, have different weights in each formula. Understanding which one matters more helps you edit efficiently.
| Variable | Effect on Reading Ease | Effect on Grade Level |
|---|---|---|
| Sentence length (ASL) | -1.015 per unit | +0.39 per unit |
| Syllables per word (ASW) | -84.6 per unit | +11.8 per unit |
Syllable complexity has by far the largest impact. Swapping a 3-syllable word for a 1-syllable synonym does more for your score than shortening several sentences. In practice, both matter, but if you are struggling to improve your score, word choice is the higher-leverage lever.
The score is a signal, not a verdict. A 65 does not mean your writing is good; it means your sentence length and word complexity are in the right range. Pair it with a human read.
If your Reading Ease is too low (text too hard), start here:
Quick test: Paste a paragraph you think is too complex into the scorer above. Rewrite with the tips above, then compare the new score.
Word includes a built-in Flesch-Kincaid checker. Go to File -> Options -> Proofing, check "Show readability statistics", then run spell check. The readability panel appears at the end and shows both Reading Ease and Grade Level.
Get Flesch Reading Ease, Grade Level, sentence analysis, and writing improvement suggestions for any text, all in one place.
Open Readability Checker Word CounterFor most web content, 60-70 is the target range. Scores of 70-80 are easier and suit general consumer audiences. Below 50 is considered difficult and is more appropriate for academic or technical writing.
For general web content, a Grade Level of 6-8 is recommended. This corresponds to middle school reading level and is accessible to the widest online audience. Academic writing typically sits at Grade 12+.
Flesch Reading Ease scores 0-100 where higher means easier. Flesch-Kincaid Grade Level scores on a US school grade scale where lower means easier. They use the same inputs but different formulas and opposite scales.
To raise your Reading Ease score, shorten sentences and use simpler words. Split sentences over 20-25 words. Replace multi-syllable words with shorter alternatives where meaning is unchanged.
Yes. Go to File -> Options -> Proofing, enable "Show readability statistics", then run spell check. Word displays both scores at the end of the spell check process.
Most national newspapers target a Reading Ease of around 60-70 and a Grade Level of 7-9. Tabloid-style publications typically aim higher, while broadsheets may sit slightly lower.