[{"data":1,"prerenderedAt":474},["ShallowReactive",2],{"legal-links":3,"content:en:how-we-measure-reading-levels":13},[4,7,10],{"key":5,"href":6},"terms","\u002Fen\u002Fp\u002Fterms",{"key":8,"href":9},"privacy","\u002Fen\u002Fp\u002Fprivacy",{"key":11,"href":12},"cookies","\u002Fen\u002Fp\u002Fcookies",{"page":14,"alternates":414,"books":417,"tagLabels":418,"linkableTags":469},{"parser":15,"kind":16,"status":17,"hl":18,"slug":19,"translationKey":20,"template":21,"robots":22,"title":23,"heading":24,"description":25,"updated":26,"keywords":27,"tags":34,"agent":37,"blocks":42,"sources":377,"toc":378,"words":385,"related":386},1,"page","published","en","how-we-measure-reading-levels","level-methodology","plain","noindex","How we measure reading levels · books.dev","How we measure reading levels","What a label like B2.1 means, how a program measures it from the text itself, and how we check the scale against exams, teachers and graded readers.","2026-10-19",[28,29,30,31,32,33],"reading level","CEFR","B1","B2","graded readers","adapted books",[35,36],"reading","books",{"process":38,"model":39,"at":40,"effort":41},"Correction","claude-opus-5-5","2026-10-19 16:00:00","unknown",[43,54,59,98,101,105,174,178,181,185,194,198,201,205,272,276,280,289,298,302,305,335,344,347],{"type":44,"spans":45},"paragraph",[46,48,52],{"t":47},"Every edition in the library carries a label such as ",{"t":49,"marks":50},"B2.1",[51],"b",{"t":53},". A program calculates it from the text itself: nobody types it in, and the level an adaptation was meant for does not count. The letter and the first digit are the CEFR band you know from courses and exams. The decimal shows where inside that band the text sits: B1.2 is near the easy end of B1, B1.8 near the hard end, and B1.5 is a typical B1 exam reading text.",{"type":55,"level":56,"text":57,"id":58},"heading",2,"What the label tells you","what-the-label-tells-you",{"type":60,"ordered":61,"items":62},"list",false,[63,70,77,84,91],{"spans":64},[65,68],{"t":66,"marks":67},"The band comes first.",[51],{"t":69}," B1.0 and B1.9 are both B1. The decimal is a finer position on the same scale, useful for comparing two editions.",{"spans":71},[72,75],{"t":73,"marks":74},"The label and the catalogue section are different things.",[51],{"t":76}," The B1 section holds our simplest retelling of a book; the label measures its text. Our B1-section editions usually measure between B1.8 and B2.5: they follow the original chapter by chapter and are denser than the section name suggests.",{"spans":78},[79,82],{"t":80,"marks":81},"Originals are measured on the same scale.",[51],{"t":83}," If a novel measures C2 in the original, its B2 edition might come out at C1.1 and its B1 edition at B2.1. We only publish an adaptation that is clearly easier than its original.",{"spans":85},[86,89],{"t":87,"marks":88},"C2 has no decimal.",[51],{"t":90}," Neither our program nor the other checks we tried tell C1 texts from C2 texts reliably, so everything harder than C1.9 is simply labelled C2.",{"spans":92},[93,96],{"t":94,"marks":95},"Small differences mean nothing.",[51],{"t":97}," B1.6 and B1.7 read the same in practice. A difference of half a band or more you will notice.",{"type":55,"level":56,"text":99,"id":100},"How the program measures a text","how-the-program-measures-a-text",{"type":44,"spans":102},[103],{"t":104},"It splits the book into passages of about 220 words and looks at each one in three ways.",{"type":106,"head":107,"rows":108},"table",true,[109,122,139,161],[110,114,118],{"spans":111},[112],{"t":113},"Signal",{"spans":115},[116],{"t":117},"What it looks at",{"spans":119},[120],{"t":121},"Weight in the score",[123,127,135],{"spans":124},[125],{"t":126},"Neural classifiers",{"spans":128},[129,131,133],{"t":130},"Three open models trained to estimate the CEFR level of an English text",{"ref":15,"url":132,"first":107},"https:\u002F\u002Fhuggingface.co\u002FAbdullahBarayan\u002FModernBERT-base-doc_en-Cefr",{"t":134},". They read the whole passage: the words, the grammar and how the ideas connect.",{"spans":136},[137],{"t":138},"70%",[140,144,157],{"spans":141},[142],{"t":143},"Words",{"spans":145},[146,148,150,152,155],{"t":147},"The average CEFR level of the words, from the CEFR-J",{"ref":56,"url":149,"first":107},"http:\u002F\u002Fwww.cefr-j.org\u002Fdownload.html",{"t":151}," and Octanove",{"ref":153,"url":154,"first":107},3,"https:\u002F\u002Fgithub.com\u002Fopenlanguageprofiles\u002Folp-en-cefrj",{"t":156}," wordlists, and how many rare words the text uses.",{"spans":158},[159],{"t":160},"25%",[162,166,170],{"spans":163},[164],{"t":165},"Sentences",{"spans":167},[168],{"t":169},"How long the longest sentences are and how deeply clauses sit inside one another.",{"spans":171},[172],{"t":173},"5%",{"type":44,"spans":175},[176],{"t":177},"The passages are combined into one score for the whole book, and the score becomes the label: 4.31 is B2.3. Words explained in brackets are measured together with their explanation, the way you read them.",{"type":55,"level":56,"text":179,"id":180},"How we set the scale","how-we-set-the-scale",{"type":44,"spans":182},[183],{"t":184},"The weights and the conversion from score to label were fitted on 200 reading texts from the free sample papers of four exam boards — Cambridge English, LanguageCert, Pearson and Trinity College London — from A2 to C2: a typical exam text of a band gets the middle of that band (B2.5 for B2). We tested it fairly: each time the program was fitted without one exam board and then measured that board's texts unseen.",{"type":44,"spans":186},[187,189,192],{"t":188},"Exam texts are articles and letters; our books are novels. So we checked separately whether the program confuses genres, on 4,724 passages whose difficulty teachers rated by comparing them in pairs",{"ref":190,"url":191,"first":107},4,"https:\u002F\u002Fwww.commonlit.org\u002Fblog\u002Fintroducing-the-clear-corpus-an-open-dataset-to-advance-research-28ff8cfea84a\u002F",{"t":193},". At the same teacher rating, the program placed literary passages slightly lower — by 0.13. We raised book labels by that amount.",{"type":44,"spans":195},[196],{"t":197},"The method has a version number, and a version in use never changes: the same text always gets the same label. When we improve the method, a new version comes out and every edition in the library is measured again. The current version is 1.2 (since 13 October 2026).",{"type":55,"level":56,"text":199,"id":200},"How we check the scale","how-we-check-the-scale",{"type":44,"spans":202},[203],{"t":204},"A scale is only as good as its agreement with texts whose level is already known.",{"type":106,"head":107,"rows":206},[207,220,233,246,259],[208,212,216],{"spans":209},[210],{"t":211},"Texts of known level",{"spans":213},[214],{"t":215},"How many",{"spans":217},[218],{"t":219},"Our label (median)",[221,225,229],{"spans":222},[223],{"t":224},"Exam, A2 · B1 · B2",{"spans":226},[227],{"t":228},"19 · 35 · 59",{"spans":230},[231],{"t":232},"A2.9 · B1.6 · B2.6",[234,238,242],{"spans":235},[236],{"t":237},"Exam, C1 · C2",{"spans":239},[240],{"t":241},"46 · 49",{"spans":243},[244],{"t":245},"C1.6 · C1.6",[247,251,255],{"spans":248},[249],{"t":250},"Graded readers, A2 · B1",{"spans":252},[253],{"t":254},"42 · 62",{"spans":256},[257],{"t":258},"B1.0 · B1.5",[260,264,268],{"spans":261},[262],{"t":263},"Graded readers, B2 · C1",{"spans":265},[266],{"t":267},"19 · 12",{"spans":269},[270],{"t":271},"B1.9 · B1.9",{"type":44,"spans":273},[274],{"t":275},"What this shows. Up to C1 our labels match the exam level within half a band. The program does not tell C2 texts from C1 texts, which is why C2 has no decimal. Graded readers from the Cambridge, Penguin and Helbling series at B2 and C1 measure upper B1 on our scale. That is not a disagreement but a different question: a series labels a book by the reader who will find it easy, while our label measures the text itself, the way an exam measures a reading text.",{"type":44,"spans":277},[278],{"t":279},"We also checked the program against two independent methods. Language models from other developers compared passages for difficulty and agreed with the teachers even better than the program does; they too placed our editions above series books of the same band. A vocabulary count shows the same: in our B1 editions 2.2% of the words fall outside the 2,000 most frequent, against 1.5% in series B1 books and 2.5% in series B2 books.",{"type":44,"spans":281},[282,284,287],{"t":283},"The originals of classic novels measure between C1.2 and C2 on our scale. The CEFR itself puts them there too: reading “classical” literary writing is described at C2, “contemporary” literary texts at C1, and novels in “straightforward, unelaborated language” at B2",{"ref":285,"url":286,"first":107},5,"https:\u002F\u002Frm.coe.int\u002Fcefr-companion-volume-with-new-descriptors-2018\u002F1680787989",{"t":288},".",{"type":290,"tone":291,"title":292,"blocks":293},"callout","tip","If you are used to graded readers",[294],{"type":44,"spans":295},[296],{"t":297},"Our editions follow the original closely, chapter by chapter, so they are denser than most series books of the same band: one of our B1-section editions reads about like a series' B2 book. Compare labels rather than section names, and start with an edition half a band below your level.",{"type":44,"spans":299},[300],{"t":301},"The medians rest on hundreds of texts, so they are stable; a single short text can still differ from its level by up to a band, which is why we label whole books, not passages. A book's label is accurate to about half a band.",{"type":55,"level":56,"text":303,"id":304},"What the label does not tell you","what-the-label-does-not-tell-you",{"type":60,"ordered":61,"items":306},[307,321,328],{"spans":308},[309,312,314,319],{"t":310,"marks":311},"It measures the text, not you.",[51],{"t":313}," To find your own level, take the ",{"t":315,"to":316},"vocabulary test",{"kind":317,"path":318},"app","\u002Fvocab\u002Ftest",{"t":320}," and start with an edition of your band.",{"spans":322},[323,326],{"t":324,"marks":325},"It is not an exam result.",[51],{"t":327}," No program can certify a text the way an exam board certifies a candidate; the label is a careful estimate on one consistent scale.",{"spans":329},[330,333],{"t":331,"marks":332},"It does not measure the story.",[51],{"t":334}," Two books with the same label can feel different: an old novel keeps its period objects and customs. The words a story needs are kept and explained in brackets where they first appear.",{"type":44,"spans":336},[337,339,343],{"t":338},"How to choose a book at your level and actually finish it is in ",{"t":340,"to":341},"how to read books in English",{"kind":16,"hl":18,"slug":342},"how-to-read-books-in-english",{"t":288},{"type":55,"level":56,"text":345,"id":346},"Questions","questions",{"type":348,"items":349},"faq",[350,359,368],{"q":351,"a":354},[352],{"t":353},"Why does an edition in the B1 section have a B2 label?",[355],{"type":44,"spans":356},[357],{"t":358},"The section is our simplest retelling of the book; the label measures its text. We retell the whole novel without cutting the plot, and on the exam scale such a text usually sits on the line between B1 and B2. We show the measurement as it is so you can choose by it.",{"q":360,"a":363},[361],{"t":362},"Why does B1 here not match B1 in my coursebook?",[364],{"type":44,"spans":365},[366],{"t":367},"Exams, publishers and apps each place texts on the CEFR in their own way, and their scales differ by up to a band. Our scale is set on exam reading texts; graded-reader series sit below their own labels on it from B2 up. Use the band as a guide and trust how the first pages read to you.",{"q":369,"a":372},[370],{"t":371},"Can the label of a book change?",[373],{"type":44,"spans":374},[375],{"t":376},"Only when we release a new version of the method. Then every edition is measured again at the same time, never one book at a time. That happened on 13 October 2026: version 1.2 raised the labels because the previous one read the top of the scale too low.",[132,149,154,191,286],[379,380,381,382,383,384],{"id":58,"text":57,"level":56},{"id":100,"text":99,"level":56},{"id":180,"text":179,"level":56},{"id":200,"text":199,"level":56},{"id":304,"text":303,"level":56},{"id":346,"text":345,"level":56},1269,[387,391,394,398,402,406,410],{"hl":18,"slug":388,"title":389,"description":390},"ai","AI Disclosure","Where books.dev uses machine-written text and synthetic speech, how it is labelled, and what Article 50 of the EU AI Act requires us to tell you about it.",{"hl":18,"slug":342,"title":392,"description":393},"How to Read a Book in English and Actually Reach the Last Page","A plan for reading your first English book to the end: a three-page test, a 14-day start, and what to do when you want to quit.",{"hl":18,"slug":395,"title":396,"description":397,"auto":107},"english-audiobooks","English audiobooks: how to listen and read at the same time","Why listening alone teaches little, and how one page and three passes turn an English audiobook into practice. The voice is synthetic; the text stays on screen.",{"hl":18,"slug":399,"title":400,"description":401,"auto":107},"english-books-b1","English books and audiobooks for B1 learners","What to read and listen to in English at B1, free: whole classic novels in versions that follow the original, how to pick your first one and finish it.",{"hl":18,"slug":403,"title":404,"description":405,"auto":107},"english-books-b2","English books and audiobooks for B2 learners","What to read and listen to in English at B2, free: Dracula, Jane Eyre, Sherlock Holmes in editions that follow the original. How to choose, and when to try originals.",{"hl":18,"slug":407,"title":408,"description":409,"auto":107},"english-books-c1","English books and audiobooks for C1 learners","What to read and listen to in English at C1, free: classic novels in the original and editions close to it. How to handle nineteenth-century English.",{"hl":18,"slug":411,"title":412,"description":413,"auto":107},"english-books-for-beginners","English books for beginners: where to start","There are no A1 or A2 books on the shelf, so here is a path: learner stories first, then a two-minute page test and five easy B1 editions to start with.",{"en":19,"ru":415,"es":416},"kak-my-izmeryaem-uroven","como-medimos-el-nivel",{},{"legal":419,"privacy":422,"security":426,"payments":430,"copyright":434,"ai":438,"accessibility":442,"account":446,"product":450,"reading":454,"vocabulary":458,"audio":462,"books":465},{"en":420,"ru":421,"es":420},"Legal","Юридическое",{"en":423,"ru":424,"es":425},"Privacy","Приватность","Privacidad",{"en":427,"ru":428,"es":429},"Security","Безопасность","Seguridad",{"en":431,"ru":432,"es":433},"Payments","Оплата","Pagos",{"en":435,"ru":436,"es":437},"Copyright","Авторские права","Derechos de autor",{"en":439,"ru":440,"es":441},"AI","Искусственный интеллект","IA",{"en":443,"ru":444,"es":445},"Accessibility","Доступность","Accesibilidad",{"en":447,"ru":448,"es":449},"Account","Аккаунт","Cuenta",{"en":451,"ru":452,"es":453},"Product updates","Обновления","Novedades",{"en":455,"ru":456,"es":457},"Reading","Чтение","Lectura",{"en":459,"ru":460,"es":461},"Vocabulary","Словарь","Vocabulario",{"en":463,"ru":464,"es":463},"Audio","Аудио",{"en":466,"ru":467,"es":468},"Books","Книги","Libros",[470,36,471,472,473,8,35],"account","copyright","legal","payments",1792358487684]