You can check out above graph to see how the market cap of Bitcoin has changed over time. The market cap value depends on the value of Bitcoin on that particular day and number of Bitcoin in supply at that day.

How is Bitcoin Market Cap calculated?

The Bitcoin Market cap is calculated using a simple formula. You can find it below:

Bitcoin Market Capitalization in USD = Number of BTC in supply X Price of one Bitcoin in USD

Since the price of Bitcoin is highly volatile you can see the market cap going up and down a lot. Sometimes price and market cap are not linear to each other due to increase in the supply of coins in the market and stable or decrease in the price of the coin. So you can say that it's not simple to predict the market cap of Bitcoin or predict the price of Bitcoin.