Readability Checker: Flesch Reading Ease and Flesch-Kincaid

How it works

Paste your text into the left pane; the readability report appears on the right straight away. English text is scored with the Flesch Reading Ease formula: 206.835 − 1.015 × (words/sentences) − 84.6 × (syllables/words), so longer sentences and longer words lower the score. The report also gives the Flesch-Kincaid grade level, which translates the same two averages into a US school grade. The four-sentence lease sample has 44 words and about 59 syllables; it scores 82.2, which is "easy" (80–90), at grade level 4.5. Below the scores you get the three longest sentences with their word counts; split those first if you need a higher score. For a text in another language, choose it under "Language of the text": German, French, Spanish and Turkish each have their own published formula, and applying the English one to them gives wrong results. Leave a blank line after headings and list items so they count as separate sentences. The score measures structure only; it cannot tell whether the content is correct or clear.

This tool is also known as readability checker, flesch reading ease, flesch kincaid grade level calculator, readability score, text readability test, reading level checker.

What is Readability?

Readability is how easy or hard a text is to read because of its structure. Formulas estimate it from two measures: words per sentence and syllables per word. Long sentences force the reader to hold more in mind at once, and long words take more decoding. Readability is not the same as clarity: a text written in short sentences but full of unknown terms can score well and still not be understood.

What is LIX (readability index)?

LIX is a readability index proposed by the Swedish researcher Carl-Hugo Björnsson in 1968 that ignores syllables: it adds the average sentence length to the percentage of words longer than six letters. Because it does not count syllables, it works the same way in every language and allows a rough comparison of texts across languages. Lower is easier: under 30 is very easy, 40–50 medium, above 60 very hard. The report shows LIX for every language.

What is the difference between Flesch Reading Ease and Flesch-Kincaid?

Both use the same two inputs, average sentence length and average syllables per word, but they express the result differently. Flesch Reading Ease (1948) gives a score from 0 to 100 where higher means easier. The Flesch-Kincaid grade level (1975), built for US Navy training material, turns the same inputs into a US school grade where higher means harder. A text with a Reading Ease of about 60 to 70 usually lands around grades 8 to 9.

The formulas and where they come from

Each language is scored with the formula published for it; the coefficients are taken from the primary sources below. English: Flesch = 206.835 − 1.015 × words/sentences − 84.6 × syllables/words; Flesch-Kincaid grade = 0.39 × words/sentences + 11.8 × syllables/words − 15.59. German: Amstad = 180 − words/sentences − 58.5 × syllables/words. French: Kandel-Moles = 207 − 1.015 × words/sentences − 73.6 × syllables/words. Spanish: Szigriszt-Pazos = 206.835 − 62.3 × syllables/words − words/sentences. Turkish: Ateşman = 198.825 − 40.175 × syllables/words − 2.610 × words/sentences. LIX = words/sentences + 100 × (words longer than 6 letters)/words; it ignores syllables and works the same in every language.

The Spanish Fernández Huerta formula, as published, uses "sentences per 100 words" in its last term, so shorter sentences lower the score. Law (2011) showed this is a fraction inverted while adapting Flesch; this tool uses the corrected form: 206.84 − 60 × syllables/words − 1.02 × words/sentences.

• Ateşman, E. (1997). Türkçede okunabilirliğin ölçülmesi. Dil Dergisi, 58, 71-74.
• Flesch, R. (1948). A new readability yardstick. Journal of Applied Psychology, 32(3), 221-233.
• Kincaid, J. P., Fishburne, R. P., Rogers, R. L., Chissom, B. S. (1975). Derivation of new readability formulas for Navy enlisted personnel. Research Branch Report 8-75.
• Amstad, T. (1978). Wie verständlich sind unsere Zeitungen? Doctoral thesis, Universität Zürich.
• Bamberger, R., Vanecek, E. (1984). Lesen – Verstehen – Lernen – Schreiben. Wien: Jugend und Volk.
• Kandel, L., Moles, A. (1958). Application de l'indice de Flesch à la langue française. Cahiers Études de Radio-Télévision, 19.
• Fernández Huerta, J. (1959). Medidas sencillas de lecturabilidad. Consigna, 214.
• Law, G. (2011). Error in the Fernandez Huerta Readability Formula. LINGUIST List 22.2332.
• Szigriszt Pazos, F. (1993). Sistemas predictivos de legibilidad del mensaje escrito: fórmula de perspicuidad. Doctoral thesis, Universidad Complutense de Madrid.
• Barrio-Cantalejo, I. M. et al. (2008). Validación de la Escala INFLESZ para evaluar la legibilidad de los textos dirigidos a pacientes. Anales del Sistema Sanitario de Navarra, 31(2).
• Björnsson, C. H. (1968). Läsbarhet. Stockholm: Liber.

How to raise the score, and what it cannot tell you

Sentence length moves the Flesch score most. Splitting a long sentence at "and", "but" or "because" raises it quickly; choosing the shorter word ("use" rather than "utilize") is the second lever. Plain-language guidance for public documents commonly aims for 60 or above, which is the "standard" band.

Limits: English spelling does not show syllables exactly, so the count is an estimate (silent -e, -ed and -es are handled, but words like "area" can be off by one); the report says so. A period in abbreviations like "Dr." or "e.g." may be read as the end of a sentence. The formula looks at length only: short nonsense sentences score high.

Frequently asked questions

What is a good Flesch Reading Ease score?

60 to 70 is "standard" and readable by most adults; 70 and above is easy, 50 and below is hard. The scale runs from 0 (very difficult) to 100 (very easy): 90–100 very easy, 80–90 easy, 70–80 fairly easy, 60–70 standard, 50–60 fairly difficult, 30–50 difficult, 0–30 very difficult.

What is the Flesch-Kincaid grade level?

It converts the same two averages (words per sentence and syllables per word) into a US school grade: 0.39 × words/sentences + 11.8 × syllables/words − 15.59. A result of 8 means a typical eighth grader, around 13 to 14 years old, can follow the text.

Can I check a text in another language?

Yes. Choose the language under "Language of the text". German uses the Amstad formula and the Wiener Sachtextformel, French Kandel-Moles, Spanish Szigriszt-Pazos (INFLESZ scale) and Fernández Huerta, Turkish Ateşman. LIX is shown for every language.

Is my text sent anywhere?

No. Counting and scoring happen entirely in your browser; the text you paste is never sent to a server or stored.