Understanding Flesch-Kincaid Reading Ease and Grade Level

An article about garden planning can come back from a readability checker scoring 38, which is the band labelled "difficult, college level." That result usually surprises the person who wrote it.

Flesch Reading Ease scores text from 0 to 100, where higher means easier, using only two inputs: average words per sentence and average syllables per word. Most web prose should land between 60 and 70. Nothing about your vocabulary, argument or accuracy enters the formula, which is both why it is quick and why it is limited.

What the Flesch Reading Ease score measures

Rudolf Flesch published the Reading Ease formula in 1948. It rates text on a 0 to 100 scale, with higher scores meaning easier reading, and it needs two variables:

• Average sentence length (ASL), the mean number of words per sentence
• Average syllables per word (ASW), the mean number of syllables per word

FRE = 206.835 − (1.015 × ASL) − (84.6 × ASW)

Shorter sentences and shorter words produce a higher score. That is the entire mechanism. The formula has no way to notice that a sentence is ambiguous, that a paragraph contradicts the one before it, or that a short word is being used in a specialist sense the reader won't know. Two texts can score identically while one is clear and the other is nonsense.

The Flesch Reading Ease bands

FRE score	Reading difficulty	Typical audience	Publication examples
90–100	Very easy	5th grade, around 11 years	Children's books
80–89	Easy	6th grade	Sports magazines
70–79	Fairly easy	7th grade	Social media, ads
60–69	Standard, plain English	8th to 9th grade	Blog posts, web copy
50–59	Fairly difficult	High school	Technical blogs
30–49	Difficult	College	Business reports
0–29	Very confusing	Graduate, specialist	Academic journals

Most blog posts belong in the 60 to 70 range, which is accessible to a general reader without feeling condescending. Marketing copy often aims a little higher, around 70 to 80, because it is read in a hurry and frequently on a phone.

The Flesch-Kincaid Grade Level

In 1975, J. Peter Kincaid adapted Flesch's work for the US Navy. The Grade Level metric uses the same two inputs and reports a US school grade instead of a 0 to 100 score:

FKGL = (0.39 × ASL) + (11.8 × ASW) − 15.59

A grade level of 8.0 means an eighth-grade reader can follow the text without rereading. Because it draws on the same two variables, Grade Level and Reading Ease always move together: you cannot raise one without moving the other. The reason to prefer Grade Level is that it communicates better to non-specialists. Telling a stakeholder their policy document reads at grade 15 lands harder than telling them it scored 32.

Target grade levels by content type

Content type	FKGL target	Reading Ease target
Social media and app copy	6–7	75–90
Blog posts, general audience	7–8	65–75
News articles	8–9	60–70
Email newsletters	8–9	60–70
Business reports	10–12	50–60
Legal and compliance	13–15	30–50
Academic research	14–16	20–40

Two rows in that table are targets you should not try to beat. Legal and compliance writing scores badly because it is built from defined terms and qualifying clauses that cannot be shortened without changing what the document means, and academic writing scores badly because its readers need the precision. A low score is a problem only when the audience did not ask for the difficulty.

What readability scores are and aren't good for

A readability score is a proxy measurement. It tells you something real about sentence length and word length, and it tells you nothing directly about whether a reader understood you.

Google has not published a readability ranking factor, and neither reading ease nor grade level is a documented ranking signal. Claims that a particular score band improves rankings, dwell time or snippet eligibility are not supported by anything Google has stated publicly, and we have measured nothing of the kind ourselves. The honest case for readability is simpler and does not depend on search engines: people finish prose they can follow, and a document nobody finishes achieves nothing regardless of where it ranks.

The other honest limit is that the formula can be gamed. Chop every sentence at the comma and your score will climb while the writing gets worse, because you have removed the connectives that told the reader how the ideas related. Use the number to find suspicious sections, then read those sections.

Four ways to move a score

1. Cut sentence length

Average sentence length is the input you have the most control over. Aim for 15 to 18 words on average, and treat any sentence over 30 as a candidate for splitting.

Before, 32 words: The researchers analyzed the data they had collected over the course of three years and found significant patterns that suggested a previously undiscovered correlation between the two variables.

After, two sentences averaging 14: The researchers analyzed three years of data. They found a previously undiscovered correlation between the two variables.

Averaging matters more than uniformity here. A page of 15-word sentences scores well and reads mechanically, so vary the lengths around the average rather than flattening everything toward it. Our guide to improving sentence structure covers how to do that deliberately.

2. Choose shorter words

Syllable count is the second input, and the substitutions are usually obvious once you look: utilize to use, ameliorate to improve, facilitate to help, demonstrate to show, subsequently to then, approximately to about.

Make the swap only where precision allows it. Approximately and about are interchangeable in prose and are not interchangeable in a specification. The formula cannot tell the difference, so you have to.

3. Unpack nominalizations

Noun-heavy phrases inflate syllable count and sentence length at the same time, which is why they are the most efficient thing to fix. Conduct an examination of becomes examine, and three words of packaging leave with it. Our guide to fixing nominalizations covers how to spot them and when to leave them alone.

4. Add visual structure

Headings, lists and short paragraphs don't enter the formula at all. They help anyway, partly because they let a reader find their place again, and partly because writing to a subheading pushes you toward shorter chunks of prose without aiming at the number directly.

Frequently asked questions

Is a high Flesch score always better?

No. The right score depends on your audience. A graduate-level research paper should score low, because that is appropriate for its readers. The aim is to match the score to the reader, not to maximise it.

Does the Flesch formula work for all languages?

The original was built for English. Adapted versions exist for Spanish, German, French and others, using different coefficients tuned to those languages' typical word and sentence lengths. An English formula applied to German text reports nonsense.

Should I aim for the same score across my whole site?

Not necessarily. Technical documentation legitimately scores lower than a FAQ page. Match each page to its reader and its purpose.

How do I calculate my readability score for free?

The Readability Checker reports Flesch Reading Ease, Flesch-Kincaid Grade Level and Gunning Fog together, with no signup. For the editing side of the job, our guide to improving readability covers what to change once you have the number.

Can I improve readability without dumbing down the content?

Yes, and the two are separate problems. Clear writing is precise writing rather than simple writing, and a difficult idea expressed in short sentences with plain words stays difficult while becoming followable. What you cannot do is remove the idea's complexity by shortening the sentences that carry it.

What's a quick way to estimate a score without a tool?

Count the words in five sentences chosen at random and average them. An average over 20 usually means a Reading Ease below 60. Under 15 and you are probably in reasonable shape, though syllable count can still pull the score down if the vocabulary is heavy.

Where to start

Run one page you already think is clear, rather than the one you suspect is bad. The score on a page you trust tells you what your own writing normally measures, and that baseline is more useful than any target band, because it turns the number into a comparison instead of a grade. Watch for the temptation to edit toward the score rather than the reader.