What is the maximum total usable supply of Bitcoin in the system?

The maximum total usable supply of Bitcoin in the system is 21 million coins. Basically, new coins are incorporated into the Bitcoin supply every 10 minutes, which is the average span of creating Bitcoin blocks. Technically, the number of Bitcoins mined per block is minimized by half after every 210,000 blocks or after four years. Satoshi Nakamoto, the anonymous Bitcoin creator, capped the total supply to 21 million so that Bitcoin could be used as a hedge against inflation.