Jack London · 1903
Roughly one unknown word in ten. Looking each one up will stall you; this one wants glosses that appear in place.
Coverage = the share of words in the text you already know. The research gives two lines: 98% before independent fluent reading is realistic, 95% for the instructional level that needs support (Hu & Nation, 2000). Proper nouns are not counted as unknown — recognising that it is a name is enough; this book has 179 of them.
Advanced — read it with glosses. 31,930 words in total; at 150 words a minute for a non-native reader, about 3 h 33 min to finish. Average sentence length 18.6 words. Reaching 95% coverage on this book (the floor for readability) takes roughly 16,250 word families.
The opening of The Call of the Wild, word for word. Tap any word you don't know and its meaning here appears beside it — no sign-up, tap as often as you like.
Buck did not read the newspapers, or he would have known that trouble was brewing, not alone for himself, but for every tide-water dog, strong of muscle and with warm, long hair, from Puget Sound to San Diego. Because men, groping in the Arctic darkness, had found a yellow metal, and because steamship and transportation companies were booming the find, thousands of men were rushing into the Northland. These men wanted dogs, and the dogs they wanted were heavy dogs, with strong muscles by which to toil, and furry coats to protect them from the frost.
Buck lived at a big house in the sun-kissed Santa Clara Valley. Judge Miller’s place, it was called. It stood back from the road, half hidden among the trees, through which glimpses could be caught of the wide cool veranda that ran around its four sides.
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Ordered by unknown words per 100. Lower reads easier; to step up a level, pick a higher number.
Computed by Readii from the public-domain text (updated 2026-10-21), not estimated by hand. The Readii reading level is our own scale, anchored on unknown-word density; it is not the same system as Lexile or AR and does not convert directly. Unknown words are counted against a frequency list built from a large subtitle corpus, so the bands mean the same thing for any learner of English, whatever your first language. This is difficulty for a non-native reader, not a native-child reading level.