We analyzed an English language dataset containing 3.8 billion words and found the following:
The relationship between dictionary size (the number of most-common words) and percentage of English is plotted above. The 98 words are listed below.
Word-usage statistics have applications that range from learning a foreign language to engineering a modern rhyming dictionary. An adult's vocabulary is about 40,000 words. However, vocabulary size increases until old age. Some words are also more common than others, so most of daily-life English uses well under 40,000 words.
We assumed a total of 200,000 distinct words and we ignored casing. A similar analysis was done by Oxford Dictionaries. They used fairly different data along with slightly different methodology. Considering the differences, though, both analyses agree quite well with one another.