Jack London · 1876
Heavy going at CET-4 level. Not unreadable — just not readable the look-every-word-up way.
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 123 of them.
Advanced — read it with glosses. 72,245 words in total; at 150 words a minute for a non-native reader, about 8 h 2 min to finish. Average sentence length 15.2 words. This book is heavy on rare, archaic and invented words: even 25,000 high-frequency word families will not reach 95% coverage — its difficulty is not in the common vocabulary.
The opening of White Fang, 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.
Dark spruce forest frowned on either side the frozen waterway. The trees had been stripped by a recent wind of their white covering of frost, and they seemed to lean towards each other, black and ominous, in the fading light. A vast silence reigned over the land. The land itself was a desolation, lifeless, without movement, so lone and cold that the spirit of it was not even that of sadness. There was a hint in it of laughter, but of a laughter more terrible than any sadness—a laughter that was mirthless as the smile of the sphinx, a laughter cold as the frost and partaking of the grimness of infallibility. It was the masterful and incommunicable wisdom of eternity laughing at the futility of life and the effort of life. It was the Wild, the savage, frozen-hearted Northland Wild.
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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 measured against the CET-4 ∪ Gaokao lists, so this is difficulty for a Chinese-speaking learner, not a native-child reading level.