Coverage

Coverage is the share of running words you recognize in what you read or hear. If you know 85 of every 100 words in a conversation, your coverage is 85%. Research on reading comprehension consistently finds a threshold effect: around 95% coverage, texts become comfortable, and around 98%, reading feels easy and new words can be learned from context alone. Below 90%, unknown words cluster thickly enough that guessing breaks down. The first 1000 English words give roughly 85% coverage of everyday speech, close enough that the remaining unknowns arrive one at a time instead of in walls.