There are over 200 Upanishads, but the Indian Culture puts a figure of 108, which is a Sacred Number. Some people have included certain Upanishads known as Principle Upanishads. These Principle Upanishads may vary in numbers. Some add 10, Some 12, Some 16. But Sri S. Radhakrishnan as picked up and compiled 18 Principle Upanishads. Read The Upanishads Below.