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Reading age calculator: Flesch-Kincaid grade level

Reading age calculator: get the Flesch-Kincaid grade level of your text, the reading age it implies and its longest sentences. Free, runs in your browser.

Runs entirely in your browser. Nothing you enter is uploaded, logged or stored.

Reading age
0

Years, as grade level plus 5

Flesch-Kincaid grade level
0

US school grade

Longest sentences

    Sentences split on . ! and ?, so abbreviations can add false sentence breaks. Syllables are counted by vowel groups, not a dictionary. Nothing you type is sent anywhere.

    Key takeaways

    • The Flesch-Kincaid Grade Level comes from a 1975 US Navy report by Kincaid, Fishburne, Rogers and Chissom.
    • The formula is 0.39 times words per sentence plus 11.8 times syllables per word, minus 15.59.
    • A grade of 8.0 means an eighth grader can understand the text, and Microsoft suggests about 7.0 to 8.0 for most documents.
    • Reading age as grade plus 5 is a convention used in grade to age tables, not part of the formula itself.
    • Sentence and syllable counts here are heuristics, so treat the result as an estimate to compare drafts.

    What it takes

    • Body text pasted or typed into the textarea

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    How to use it

    1. 1Paste the text you want to scoreUse a full paragraph or more of the real copy. The formula averages over sentences and words, so a single short line swings widely.
    2. 2Read the reading age and gradeThe grade is the Flesch-Kincaid Grade Level. The reading age is that grade plus 5 years, both shown to one decimal place.
    3. 3Check the counts behind the scoreWords, sentences, syllables and both averages are shown so you can see which of the two inputs is pushing the grade up.
    4. 4Shorten the longest sentencesThe three longest sentences are listed with their word counts. Splitting them lowers the average sentence length, and the grade drops as you type.

    A reading age is the age of a typical reader who could follow a text. This reading age calculator gets there in two steps: it computes the Flesch-Kincaid Grade Level, then adds 5 years. Both run in your browser as you type, and nothing you paste is sent anywhere.

    What does this reading age calculator measure?

    Flesch-Kincaid Grade Level. The formula was derived in a 1975 report for the US Navy by Kincaid, Fishburne, Rogers and Chissom, who recalculated readability formulas from tests of 531 Navy enlisted personnel. Microsoft, which reports the score in Word, states it as 0.39 times the average sentence length, plus 11.8 times the average syllables per word, minus 15.59. The result is a US school grade: Microsoft’s example is that 8.0 means an eighth grader can understand the document.

    Reading age. The grade plus 5. This conversion is a convention rather than part of the Navy formula. It is the offset in published grade to age tables such as Readable’s, which maps scores of 0 to 3 to ages 5 to 8 and 12 to 15 to ages 17 to 20, and puts grade 8 at a schooling age of 13 to 14.

    The weights show where edits pay off. Each extra word in the average sentence adds 0.39 of a grade; each extra 0.1 syllables in the average word adds 1.18 grades.

    How to read the results

    • Reading age and grade. Both to one decimal place. Between grades 1 and 12 a note gives the rounded grade and age, next to Microsoft’s suggested 7.0 to 8.0 for most documents.
    • Below grade 1. The formula has no floor, so very simple text can score below zero. The tool says to read this as very easy text, not as a toddler’s age.
    • Above grade 12. Past US high school, the age describes years of education more than a child’s age.
    • Counts. Words, sentences, syllables, and the two averages the formula uses.
    • Longest sentences. The three longest, with word counts. They drive the sentence-length term.

    Worked example

    The text the tool opens with is four sentences and 61 words. It reports:

    • Words: 61. Sentences: 4. Avg words / sentence: 15.3.
    • Syllables (approx.): 84. Avg syllables / word: 1.38.
    • Flesch-Kincaid grade level: 6.6. Reading age: 11.6.

    The arithmetic: 0.39 times 15.25, plus 11.8 times 84 divided by 61, minus 15.59, is about 6.61. The longest sentence is 35 words, more than twice the average. Split it into two and the grade falls.

    Common mistakes it catches, and its limits

    A high grade usually has one of two causes, and the counts show which: sentences averaging over 20 words, or a syllables-per-word figure pushed up by long abstract nouns.

    The tool shares its counting with the Flesch reading ease calculator, so the two agree on the same text. That counting is approximate. Sentences split on a period, exclamation mark or question mark followed by a space, so “Dr. Smith” adds a false break and lowers the grade. Syllables are counted by vowel groups with a silent trailing e dropped, with no pronunciation dictionary, so unusual words and names can be miscounted.

    Sources

    1. 1.Derivation of New Readability Formulas (Automated Readability Index, Fog Count and Flesch Reading Ease Formula) for Navy Enlisted Personnel - Institute for Simulation and Training, University of Central FloridaPrimary
    2. 2.Get your document's readability and level statistics - Microsoft SupportPrimary
    3. 3.Flesch Reading Ease and the Flesch Kincaid Grade Level - Readable

    Frequently asked questions

    How do you calculate reading age?

    Compute the Flesch-Kincaid Grade Level, which is 0.39 times the average words per sentence plus 11.8 times the average syllables per word, minus 15.59. That gives a US school grade. Adding 5 converts it to an approximate age, the offset readability grade to age tables use.

    Where does the grade plus 5 rule come from?

    It is a convention, not part of the 1975 formula. Readability vendors publish grade to age tables built on it: Readable's table maps a Flesch-Kincaid score of 0 to 3 to ages 5 to 8 and 6 to 9 to ages 11 to 14, which is the grade plus 5 in each case.

    What reading age should web content aim for?

    Microsoft suggests a Flesch-Kincaid grade of around 7.0 to 8.0 for most documents, which is a reading age of about 12 to 13. Readable suggests around grade 8 for text meant for the general public. Pick the level your actual readers need.

    How is this different from the Flesch reading ease calculator?

    Both use the same counts, but reading ease is a 0 to 100 score where higher means easier, while this tool gives a school grade and an age, where lower means easier. The reading ease tool also estimates reading time; this one lists your longest sentences instead.

    Why can the grade be negative or above 12?

    The formula has no floor or ceiling. Very short sentences of one-syllable words can go below zero, and dense academic text can pass 12, the end of US high school. The tool shows the raw value and a note in both cases rather than clamping it.