Free Readability Score Calculator

Readability formulas estimate how hard a text is to read from two things a computer can count: how long the sentences are and how long the words are. This calculator runs the two most widely used ones, Flesch Reading Ease and Flesch-Kincaid Grade Level, in your browser as you type, and shows the averages that feed them so you can see which of the two is pulling your score down.

Flesch Reading Ease = 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words). Rudolf Flesch published it in 1948 in the Journal of Applied Psychology ("A New Readability Yardstick"). Higher is easier. The raw formula can run past 100 or below zero, so this tool reports it on a 0–100 scale. Flesch-Kincaid Grade Level = 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59. J. Peter Kincaid and colleagues derived it in 1975 for the US Navy (Research Branch Report 8-75), recalibrating Flesch's inputs to a US school grade. A result of 8.0 means a typical eighth grader should follow the text. It has no upper limit, and this tool shows nothing below 0.

Reading Ease score bands, with the label this tool shows and the approximate US school level from Flesch's original table: 90–100 Very Easy (5th grade); 80–89 Easy (6th grade); 70–79 Fairly Easy (7th grade); 60–69 Standard, or plain English (8th–9th grade); 50–59 Fairly Hard (10th–12th grade); 30–49 Difficult (college); 0–29 Very Difficult (college graduate). The label turns green from 70, amber from 50 to 69 and red below 50. The Grade Level card adds its own label: Kindergarten below grade 1, Elementary up to grade 5, Middle School up to 8, High School up to 12, College up to 16 and Graduate above that.

How the counts work: a sentence ends at a period, question mark or exclamation point; a word is anything separated by spaces; syllables are estimated from groups of vowels, with a silent final e and endings such as -ed and -es dropped, and every word of three letters or fewer counted as one syllable. That estimate is right for most everyday words and off by one on some ("searches" counts as one syllable). This is also why two readability checkers rarely agree to the decimal, since each counts syllables and sentence breaks a little differently.

Worked example. "When you are planning a content calendar for the next quarter, it is important to consider which topics your audience actually searches for and how each article will support the products you sell." That is one sentence of 33 words and 50 syllables, or 1.52 syllables per word: Reading Ease 45.2 (Difficult) and Grade Level 15.2 (College). Rewritten as "Plan next quarter's content around what your audience searches for. Then check that each article supports a product you sell." it becomes 2 sentences, 20 words and 28 syllables: Reading Ease 78.2 (Fairly Easy) and Grade Level 4.8 (Elementary). Most of the gain came from splitting the sentence, which is usually the fastest fix. Cutting filler such as "it is important to" handles most of the rest.

Common mistakes that skew the score. Headings and bullet points without a closing period merge into the next sentence, which inflates words per sentence, so paste body copy only or end each item with punctuation. Decimals, abbreviations such as "e.g." and URLs add false sentence breaks and make text look easier than it is. Very short samples swing wildly, because a single sentence break moves the averages a lot, so test at least a few paragraphs. Finally, chasing a number by chopping every sentence into fragments produces text that scores well and reads badly. Vary the rhythm, and use a passive voice detector and a transition word checker to fix what the formula can't see.

What these formulas don't measure: whether the reader knows the topic, whether the argument is in a sensible order, or how the page is laid out. Flesch and Kincaid built them for general prose and training manuals, and a short, familiar technical term like "API" scores as easy while a long common word like "information" scores as hard. Google doesn't publish a readability score it wants. Its guide to creating helpful, people-first content asks whether content has spelling or stylistic issues and whether it looks well produced or hastily done, and clear writing helps on both.

Want articles that read cleanly without the editing pass? Skribra researches, writes and publishes long-form articles to your CMS every day, in a natural, plain-spoken voice tuned to your audience rather than to a formula.