DataToolsLab

Text Analysis Tools

Measure how a piece of writing reads rather than what it says. Work out a reading speed in words per minute from a timed passage, turn it into pages per hour, and see how many days a book will take at the minutes a day you actually have. Then the structure: sentence lengths and their distribution, average word length both as letters and as characters, vocabulary diversity, lexical density, and a paragraph-by-paragraph table of a whole document. The five readability formulas — Flesch Reading Ease, Flesch-Kincaid, Gunning Fog, SMOG and the Automated Readability Index — all run on one shared statistics module, so the differences between them are differences of formula rather than of counting, and each page shows the others beside its own score.

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Reading Speed & Volume

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Readability Formulas

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About Text Analysis Tools

Readability is not one number. The five established formulas disagree with each other by two or three grades on the same passage, because they were derived from different populations for different purposes: Flesch and Flesch-Kincaid from US Navy technical manuals, Gunning Fog from newspaper training, SMOG from comprehension testing in health information, and the Automated Readability Index from typewritten letters rather than syllables. A single figure presented alone invites the reader to treat it as a measurement, so every formula page here runs all five on the same text and shows them side by side. Underneath them is one shared engine — a sentence splitter that masks decimal points, abbreviations and initials before it splits; a tokeniser that keeps internal apostrophes and hyphens; a syllable counter that is a documented heuristic rather than a dictionary; and a stop-word test for lexical density. That is what makes the comparison meaningful, and it is also why the tools are explicit about what is approximated: syllables are estimated, SMOG's 30-sentence sampling requirement is stated on the page, and the grade bands are labelled estimates rather than measurements. Nothing duplicates a neighbouring category — plain word and character counting is in Text Tools, markdown structure in Markdown Tools, page and paper arithmetic in Document Formatting, and reading plans in Student Scheduling. Everything runs in your browser, with no upload and no account.

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Frequently asked questions

Which readability formula should I use?

It depends on what the number is for, and the tools show all five on the same text so the choice is visible rather than hidden. Flesch Reading Ease is the most widely quoted and the easiest to explain, so it is the right headline number for a style guide. Flesch-Kincaid and the Automated Readability Index give a US school grade, which is what a plain-language standard usually specifies. Gunning Fog is the one to use when sentence length and vocabulary should count equally. SMOG is the one the health and patient-information literature validated against comprehension tests, but it needs at least 30 sentences — about 600 to 700 words — before the figure is the formula rather than an approximation of it.

Why do the five formulas give different grades for the same text?

Because they measure different things, and because they were derived from different populations. Flesch and Flesch-Kincaid weight vocabulary far more heavily than sentence length; Gunning Fog weights the two equally; SMOG ignores sentence length entirely and counts only three-syllable words. Fog counts every polysyllable while the original method strips proper nouns and -ed and -es endings, so it reads slightly high here. A spread of two or three grades between the five is normal, and the interesting signal is not the average but which ones disagree and why.

How accurate is the syllable counting?

Close on ordinary prose and wrong by a syllable on words like queue, business and every. It counts vowel groups with a rule for a silent final e and a rule for the consonant-plus-le ending, which gets most words right without a pronunciation dictionary; nothing short of a dictionary is exact. Every syllable-based formula inherits that approximation, which is why the grade bands are labelled estimates. The Automated Readability Index is the exception — it counts letters and words, both of which are counted exactly, so its result is reproducible to the digit and can be used to sanity-check the others.

Is my text uploaded or stored anywhere?

No. Every tool in this category runs entirely in your browser — there is no account, no server round-trip and no length limit, and an open page keeps working offline once it has loaded. That matters for this category in particular, because the text people paste in tends to be unpublished work. The flip side is that nothing is stored: closing the tab clears what you typed, so anything worth keeping should be copied or printed first.

Does a high reading grade mean the writing is bad?

No — it means the writing is hard, which is sometimes the point. A legal definition, a peer-reviewed paper and a technical manual all score above grade 16 and all should. The formulas are useful when a text has to reach a stated audience and is not reaching it: patient information that should be readable at grade 8, a web page aimed at a general reader, a textbook chapter set for a specific year group. Read the band as a description of difficulty rather than as a mark out of ten.

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