Last update: 13. June 2025
Calculating the readability online
This page lists online tools that you can use to analyze your texts. It is easy, you just copy and paste your text into a window, sometimes also a URL can be specified. The most tools are limited to texts in English. If a language is not mentioned in the description of a tool, only the readability analysis of English texts gives valid results.
Please note the data privacy statements of some websites. Your data may be stored or even given away to third parties without your allowance. Thanks to Karen Smiley for this information.
Many programs were excluded from this page, these are at the bottom of this page. One reason is that the overviews I used are listing SEO tools, and readability is only one aspect.
Maybe you would like a test of all tools? I found none on the web so I think I will do that with a few data sets.
The readability formulas are often named by the authors. You should know that there are some formulas that have different versions: Dale-Chall, Spache, Coleman-Liau, Automated readability index (ARI). Also Flesch's formulas have been adapted for special purposes from different authors. Often you will find that the version of the formula is not mentioned.
| Autocrit |
website:
Autocrit
formulas supported: new Dale-Chall, Spache revised, Flesch-Kincaid, Linsear Write, Flesch reading ease, lexical density test
results: all readability formulas, number of words, char/words, syllables/word
output all formulas are given and explained, free basic version
remarks: Autocrit is badvanced has interacting tools and comparing your text with other authors. The newer version of Dale-Chall and Spache were used.
| Cathoven |
website:
Cathoven Readability Checker
formulas supported: Flesch reading ease, Flesch-Kindcaid grade, Gunning FOG,SMOG, ARI, Coleman-Liau, Linsear Write, Dale-Chall, McAlpine
country/state: no imprint, e-mail only via contact form
results: results of the readability formulas, school levels (US),
output readability consensus that seems to be a mixture of all formulas, word count, sentence, count, average sentence length, results can be downloaded, the text can be edited for another analysis
remarks: This design is clear, but it is not clear which version of Dale-Chall and Coleman-Liau were used.
| CefrLex |
website:
CefrLex
formulas supported: no readability formulas, but classifies the text in language leaeearn levls from A1 to C2
results: contains common word for 2nd language learns in different languages language level, difficulty of words in different colours
output: language level of the text, e.g. A2 or B1
remarks: none yet
| Coh-Metrix |
website:
Coh-Metrix
formulas supported:Flesch-Kincaid Grade Level readability formula (Kincaid, Fishburne, Rogers, & Chissom, 1975).
results: Coh-Metrix is a program that uses natural language processing to analyze discourse. It calculates a number of linguistic indices related to various aspects of language that can be used to determine the quality, readability, or other specific properties of a written or spoken text.
output: second language level
remarks: seems to be outdated, desktop tools can be downloaded on request.
| Character Calculator (CC) |
website:
Character Calculator (CC)
formulas supported: Flesch reading ease, Flesch-Kincade grade, SMOG, Gunning Fog, Dale-Chall, syllable counter user data are stored for one week. Only english texts
results: Character Calculator is an online tool for counting characters, words, sentences, and paragraphs. It also includes a Dale-Chall Readability Calculator to score your content. SMOG score and grade provided, which is not the same.
output: Flesch reading ease, Flesch-Kincade grade, SMOG, Gunning Fog, Dale-Chall
remarks:The input data are stored on US servers, the website is operated from Turkey, the data are deleted after one week. It is unclear which vesion of Dale-Chall is used.
| CheckReadability |
website:
CheckReadability
formulas supported: ARI, Fleschreading Ease, Flesch--Kincaid, gunning Fog, Smog, Coleman-Liau, Linsear Write, Forcast, new Dale-Chall
results: values of the implemented readability formulas
output: Flesch reading ease, Flesch-Kincade grade, SMOG, Gunning Fog, Dale-Chall
remarks: All formulas are displayed with the results of the text. One can read more details on the formulas and how to interpret the results. No information on the owner of the website or if data are stored or passed to other companies.
| CIRTC |
website:
CIRTC
formulas supported: ARI, Flesch Reading Ease, Flesch-Kincaid, Gunning Fog, Smog, Coleman-Liau, SMOG, Linsear Write, Forcast
results: ARI, Flesch Reading Ease, Flesch-Kincaid, Gunning Fog, Smog, Coleman-Liau, SMOG, Linsear Write, Forcast
output: All formulas are given, also rules and assumptions are presented. Results can be copied to clipboard
remarks: none yet
| Clickhelp |
website:
Clickhelp
formulas supported: ARI, Flesch Reading Ease, Flesch-Kincaid, Gunning Fog, Smog, Coleman-Liau, SMOG, Linsear Write, Forcast
results: Flesch-Kincaid Grade Level, Coleman-Liau, Flesch Reading Ease, Gunning Fog, Automated Readability Index, Linsear Write, SMOG, FORCAST Grade, New Dale-Chall, Average Grade
output: Flesch-Kincaid Grade Level, Coleman-Liau, Flesch Reading Ease, Gunning Fog, Automated Readability Index, Linsear Write, SMOG, FORCAST Grade, New Dale-Chall, Average Grade, also text metrics
remarks: none yet
| Datayze |
website:
Datayze
formulas supported: ARI, Flesch Reading Ease, Flesch-Kincaid, Gunning Fog, Smog, Coleman-Liau, SMOG, Linsear Write, Forcast
results: Flesch Reading Ease, Gunning Fog, Flesch-Kincaid, SMOG, Dale-Chall, Fry readability grade level
output: all readability values are calculated by paragraph, not the whole text. It is not specified, which version of Dale-Chall is used.
remarks: All formulas are given, also rules and assumptions are presented. Results can be copied to clipboard. User data stored up to one year, but not given away. Minimum file size 30 sentences, not standardized.
| Editpad |
website:
Editpad
formulas supported: Flesch-Kincaid Reading Ease and grade level, Coleman-Liau, Ari
results: all values of readability formulas, Flesch's formulas are mixed up, version of Coleman-Liau not specified
output: all readability values, number of sentences and syllables
remarks: none yet
| Good calculators |
website:
Good calculators
formulas supported: Flesch Reading Ease and Flesch-Kincaid, formula given
results: all readability formulas
output: all the formulas given, words/sentence, syllables/word, senences, words
remarks: just another calculator
| Gorby |
website:
Gorby
formulas supported: ARI, Coleman-Liau, Dale-Chall, Flesch Reading Ease, Flesch-Kincaid, Smog, Gunning Fog, Spache
results: all readability formulas
output: words, sentences, longest and shortest sentence, unique words (types), words/sentence, chars/word, sentences, words, characters(with and without spaces), number of syllables missing
remarks: find readability scores at left menu, all formulas are explained and all values inserted so one can see which values where used for the computation. Difficult words are shown also within the complete text. However, it is not clear which versions of Dale-Chall and Spache were used.
| GoWinston.ai |
website:
GoWinston.ai
formulas supported: Flesch-Kincaid only
results: the analysis didn't work: There was an error. Please try again later.
output could not be tested
remarks: The website is available in English, French, Spanish, German, Portugese and Chinese.
| Gunning Fog calculator |
website:
Gunning Fog calculator
formulas supported: Gunning Fog Index only
results: Gunning Fog Index
output: long words are shown in blue, sentence boundaries are shown in red, index value shown as well as number of wentences and words
remarks: Nice idea, but abbrevation or multiple points are not excluded, so the number of sentences is biased - too high which lowers the readability results and so the text seems to be easier than it really is.
| Health Literacy Editor |
website:
Health Literacy Editor
formulas supported: reading grade, formula unclear
results: all formulas
output: highlights unfamiliar words, passive voice, density, TTR, long words more than 2 syllables, long sentences, uncommon words (e.g. erotic words)
remarks: none yet
| Hemingway |
website:
Hemingway
formulas supported: Flesch Reading Ease
results: ARI only
output: Highlights complex sentences in yellow, marks passive voice in green, points out adverbs in blue, suggests simpler words for complex ones in purple, flags very hard-to-read sentences in red
remarks: There is only one readabiility formula supported, but the highlighting of difference phenomena is useful.
| infyways |
website:
infyways
formulas supported: Flesch Reading Ease, Flesch-Kincaid, Gunning Fog, SMOG, Coleman-Liau, ARI, Linsear Write
results: all readability formulas (see above)
output: words, letters, complex words
remarks: The same company offers another tool named Text Analyzer Tool. Tests whow that both programs differ in number of letters and sentences.
| Juicy Studios online readability tester |
website:
Juicy Studios online readability tester
formulas supported: Gunning Fog, Flesch Reading Ease, Flesch-Kincaid
results: all readability formulas (see above)
output: sentences, words, words/sentence, words with 1, 2, 3, 4 and more syllables. % of words with 3 syllables and more, all readability formulas explained including the formula
remarks: The information of the distibution of syllables is useful.
| myessaywriter.ai |
website:
myessaywriter.ai
formulas supported: Flesch-Kincaid, Gunning Fog, Smog, Ari, Coleman-Liau
results: could not be tested
output: could not be tested
remarks: There is a limit of 1500 words, and you have to sign-up for free first. Nice: Selection of the readability formulas by age of the recipients. Your data are encrypted and never passed to third parties.
| NHS Medical Document Readability Tool |
website:
NHS Medical Document Readability Tool
formulas supported: result of unknown formula (reading age UK)
results: unknown readability formula
output: complex, passive, sentences and words, long words in different colours, metrics: words, sentences, avg words/sentence, sentences/paragraph, characters
remarks: The readability formula used is not speicied. This tool highlights potential problems in different colours.
| Okapi |
website:
Okapi
formulas supported: Spache wordlist from 1974, Dale-Chall (4 and more) and Spache (1-3)
results: due to access problems none
output: complex, passive, sentences and words, long words in different colours, metrics: words, sentences, avg words/sentence, sentences/paragraph, characters
remarks: Due to acess problems not possible at the moment.
| Originality.ai |
website:
Originality.ai
formulas supported: Flesch Kincaid Reading Ease and Grade Level, ARI, Coleman-Liau, Gunning Fog, SMOG, Power, Sumner, Kearl, Forcast, Dale-Chall, Spache, Linsear Write
results: all readability formulas
output: all formulas are given
remarks: You cannot test the program without sign-up. Linsear Write is not standardized nor explained, no definition of difficult words, which versions of Dale-Chall and Spache were used.
| Prepostseo |
website:
Prepostseo
formulas supported: Flesch Kincaid Reading Ease and Grade Level, ARI, Coleman-Liau
country/state: Enzipe Software House, Faisalabad, Pakistan
results: all readability formulas
output: sentences, syllables, words, keywords, unique words, total chars (without spaces) chars/words, words/sentence, syllalbes/word, syllables/sentence, longest sentences, limited word frequencies called density also for collocations
remarks: limit 5000 words. the keywords are not defined, nice text metrics and collocatinos containing two or three words.
| Readability calculator |
website:
Readability calculator
formulas supported: Coleman Liau index, Flesch Kincaid Grade Level, ARI (Automated Readability Index), SMOG
country/state: b>unknown yet
results: all readability formulas
output: text metrics: characters, words, sentences, chars/word, syllables/word, words/sentence, list of sentences for rewrite
remarks: a qquick and easy to use tool
| Readable.com |
website:
Readable.com
formulas supported: Flesch Reading Ease, Flesch-Kincaid, Gunning Fog in the free online version, many more in the full version but only for English texts: Smog, Ari, Spache (verison not mentioned), new Dale-Chall, Powers-sumner-Kearl, Raygor readability graph, Fry Readability graph, IELTS, CEFR, Lix, Rix, Forcast, Linsear Write (misspelled Lensear)
country/state: Added Bytes Ltd, Hassocks, UK
results: all readability formulas including explanations
output: count words, sentences, paragraphs, sentences > 30 syllables, words > 12 letters, adverbs, cliché (overused phrases), some phenomena are coloured: grey: long words, blue underline: grammar issue, red underline: spelling issue
remarks: export requires a trial vesion (free for 7 days), results are exported in CSV and PDF format, text can be exported in word, open document, pdf, html, latex. The are also word analyzers for different word lists so one can see the known words: Dale-Chall, Dolch, Ogden, Spache and Fry. The full version has even more readability formulas. Remarkable: there is a typo Lensear instead of Linsear. The company also offers an API that returns the results. In total: a nice website that has lots to offer.
| ReadabilityFormula |
website:
ReadabilityFormula
formulas supported: Flesch-Kincaid, Ari, Coleman-Liau, Flesch Reading Ease, Gunning fog, Smog, Linsear write, Forcast, Fry Graph, Raygor graph, new Dale-Chall, Fry Sight, Spache
country/state: Brian Scott
results: all readability formulas, with formulas and all values inserted so one check the calculation, options are available for sentence count, inflected words, compound words, proper nouns (familiar/unfamiliar), handle numbers, URLs, e-mail addresses
output: text metrics: characters, words, sentences, paragraphs, hard words, long sentences, adverbs, hard adjectives, nominals, passive words, weak verbs
remarks: Many formulas and useful options, the output shows many details how to check the validity of the results. Als text metrics give a lot of explanation, although many of these are not explained, e.g. long sentences, hard adjectives etc. These are shown in extra tabs.
| Sitechecker |
website:
Sitechecker
formulas supported: Gunning Fog, Flesch Reading Ease
country/state: Cyber Circus Limited, Gibraltar
results: all readability formulas
output: text metrics: characters, words, sentences, pages, suggestion which sentences to fix
remarks: a quick and easy to use tool, but only two formulas
| Spanish Readability |
website:
Spanish Readability
formulas supported: Fernández Huerta, The Szigriszt-Pazos Perspicuity, Inflesz Scale, Gutiérrez de Polini, Miguel Muñoz Baquedano and José Muñoz Urra, Spanish SMOG Formula (SOL), Flesch-Kincaid Grade Level (SOL), Spaulding Readability Formula, Crawford's Readability Score, García López Readability FormulaSpanish Fry Graph
country/state: b>unknown yet
results: all readability formulas and their formulas including values so you can check the calcution.
output: text metrics: characters, letters, syllables, words, sentences, paragraphs, Spaulding rare words, words/sentence, longest words, syllables/word, words with 1, 2, 3 and 4+ syllables
remarks: A specialized site for Spanish texts. Sentences must end with a sentence marker like .?! Personal data are not sold or rented to third parties.
| STORYToolz |
website:
STORYToolz
formulas supported: Flesch-Kincaid, ARU, Coleman-Liau, Fleschreading ease, Lix, Smog
country/state: Chuck Heintzelman
results: all readability formulas
output: text metrics: chars, words /chars/word, syllables/word, sentences, words/sentence, short sentences (<7), long sentences (>22), paragraphs, sentences/paragraph, Questions, paassive sentences, longest and shortest sentence in words
remarks: You can analyse up to 5120 words. Output can be exported as PDF, Excel, or CSV file
| Textinspector |
website:
Textinspector
formulas supported: Flesch-Kincaid, Flesch Reading Ease, Gunning Fog
country/state: Weblingua Ltd, UK
results: all readability formulas
output: text metrics: overall percentage difficulty, lexical diversity voc-d, sentences, token (words), academic words percentage, Percentage of words at B1 CEFR level ttr, numbers, syllables, words with more tahn 2 syllables, syllables/sentence, words/sentence, syllalbes/words
remarks: There is a limit of 250 words for guests, if you have bigger text you have to pay. The most expensive plan allows files up to 13,000 words only. The data are cleared from the server after 6 hours. The company also offers the use of an API.
| Voyant Tools |
program:
Voyant Tools
author: who knows
distributor:
Voyant
documentation:
Voyant
download: test none, online tools
operating system: browser based app
description: These tools provide an analysis of text via file, URL, or clipboard. A readability index is calculated, but which one is not documented. It generates word lists, phrases, collocations, word grapes, word density. All words are in lower case, the following languages are supported; Arabic, Bosnian, Croatian, Czech, English, French, German, Hebrew, Italian, Japanene, Portuguese, Russian, Serbian, Spanish.
| WebFx |
website:
WebFx
formulas supported: Flesch-Kincaid, Gunning, Coleman Liau, ARI, and SMOG
country/state: Guatemala, Phillipines, and USA
results: all readability formulas
output: text metrics: number of complex words and average words per sentence
remarks: This is a nice and easy to use tool with some goodies. You can enter a text from the clipboard, a file name (HTML will be stripped). WebFx may share users’ data with TeamAI.
| Wrise free readability checker |
website:
Wrise free readability checker by Rob Truslove, Wrise
formulas supported: Flesch-Kincaid, Flesch Reading Ease, Gunning Fog, SMOG, Dale-Chall Fry Readability grade
country/state: Bury, UK
results: all readability formulas
output: text metrics: words, sentences, words/sentence, characters/word, syllables/word, percent of difficult words (estimated)
remarks: This tool is very fast and has a nice dsign. The version of Dale-Chall is not mentioned.
| Wordcalc |
website: Wordcalc
formulas supported: Flesch-Kincaid Reading Ease, Gunning Fog, Coleman-Liau, SMOG, ARI, New Dale Chall , Spache
country/state:
results: all readability formulas
output: text metrics: no
remarks: Another easy to use tool that also explains the formulas itself and how to interpret the results. Also a syllable counter is offered, but this often counts one syllable too many. Also abbrevations points are not considered. If this algorithm is really used by the readability checker, your results may be biased.
Excluded software - under construction
The lists that are the basis of this section are SEO tools, and not all links use readability formulas for SEO purposes. Programs were excluded if there is no online tool available, or if only one formula is used. The following lists includes the links and the reasons why these programs were excluded.
Copywritely Flesch-Kincaid only, therefore excluded
Ginger Writing Assitant no online tool to check a text with readability formulas
Grammarly Flesch reading ease only. User data may be used for internal and external purposes therefore not included may retain random samples of de-identified text to help us improve the algorithms underlying our software and services” but “do not share the texts that you check with Grammarly with any third parties” and “have not sold, do not sell, and will not sell customer data”
Junia.ai tries to improve the readability uses Flesch reading ease, no online tool to check a text with readability formulas
Language Tool no online tool to check a text with readability formulas, verifies facts using AI for many languages
Links Assistant no online tool to check a text with readability formulas
Longshot AI no online tool to check a text with readability formulas
Okapi with current link. The online tool has a limit of 200 words. The connection to the internet is insecure. Only new Dale-chall and Spache readability formulas are im0plemented, and you select one formula from a menu dependent of the age of the readers (children).
Outwrite only afte registration you can evalute what this tool is usefule for. It seems that readability formulas are also used, but there is no further information which ones.
Searchmetrics (Conductor) no online tool to check a text with readability formulas
Surfer SEO no online tool to check a text with readability formulas
ProWritingAid no online tool to check a text with readability formulas, but tools for avoiding complex sentences or passive voice, style inconsistency checks, sentence length analysis, word choice suggestions.
Readability analyzer no online tool to check a text with readability formulas. However, you can download a*.zip file.
Readability pro the results show the grades, but not the values of each formula for Flesch-Kincaid, Gunning fog, SMOG.