We have detailed dynamic stats reported on the wiki: https://wiki.threefold.io/#/threefold__stats_token_overview_farmed
There is a number of Total liquid tokens.
You can calculate current circulating market cap = Total Liquid Tokens * Current Token Price.
For example, if we have 275M TFT in Circulation and the price of the TFT is 7c then market cap would be 19.25M USD.
Coinmarketcap reports some market capitalisation but they have their own methodology of calculating market capitalisation, therefore it may be different. We are trying to submit latest data to them from time to time to keep reported market cap there more close to the actual numbers.