The entire Chinese character corpus since antiquity comprises well over 20,000 characters, of which only roughly 10,000 are now commonly in use. However Chinese characters should not be confused with Chinese words, there are many times more Chinese words than there are characters as most Chinese words are made up of two or more different characters.
Estimates of the total number of Chinese words and phrases vary greatly. The Hanyu Da Zidian, an all-inclusive compendium of Chinese characters, includes 54,678 head entries for characters, including bone oracle versions. The Zhonghua Zihai 中华字海 (1994) contains 85,568 head entries for character definitions, and is the largest reference work based purely on character and its literary variants.Free quote
The most comprehensive pure linguistic Chinese-language dictionary, the 12-volumed Hanyu Da Cidian 汉语大词典, records more than 23,000 head Chinese characters, and gives over 370,000 definitions. The 1999 revised Cihai, a multi-volume encyclopedic dictionary reference work, gives 122,836 vocabulary entry definitions under 19,485 Chinese characters, including proper names, phrases and common zoological, geographical, sociological, scientific and technical terms.
The latest 2007 5th edition of Xiandai Haiyu Cidian 现代汉语词典, an authoritative one-volume dictionary on modern standard Chinese language as used in Mainland China, has 65, 000 entries and defines 11,000 head characters.