ATOS Analyzer vs Check Readability

ATOS Analyzer is a free web tool for estimating the readability level of text and books in English or Spanish. Users can enter a passage, analyze an entire book, or submit a sample with an estimated word count. Text can be typed or uploaded as a .txt, .docx, or .epub file, with uploads limited to 10 MB. The suggested passage length is 150 to 25,000 characters. Results include an ATOS level, grade-level equivalent, word count, AR Points, average word length, average sentence length, and language. ATOS estimates complexity on a grade-level scale using sentence length, word length, and word difficulty; its measure also accounts for book length. For a sampled book, Renaissance recommends three passages of about 150 words from different parts and an estimated total word count. Scanned documents need OCR to become recognized text before submission; changing a file extension does not convert them. The page includes a CCSS/ATOS grade-band chart for grades 1 through 12. Renaissance presents the measure as guidance for matching students with appropriately leveled reading material.

Check Readability analyzes pasted text and returns nine readability scores alongside a consensus grade level. The formulas include Automated Readability Index, Flesch Reading Ease, Gunning Fog, Flesch-Kincaid Grade Level, Coleman-Liau, SMOG, LINSEAR Write, FORCAST and New Dale-Chall. The web analyzer gives feedback on complexity, sentence length and word choice. A Chrome extension adds a native Side Panel, full-page or selected-text extraction and interactive formula breakdowns; scoring happens locally without transmitting page content or selected text. Text submitted to the website is sent over an encrypted connection and kept in memory only while scores are calculated. The site says analyzed text is not logged or stored, while Google Analytics is used for page visits and browser-related information. Check Readability is free, requires no account and permits personal and commercial use. The product says readable content can support accessibility and search rankings. Its scores are statistical estimates and cannot determine whether writing is accurate, logical, appropriate or well argued. The extension supports System, Light and Dark interface modes.