Circulating Sup ply is where things get trickier. How many of a given token are circulating? For Bitcoin it’s easy, just subtract how many haven’t been released from the max supply and you have your number. Other L1s like Ethereum and Solana either self-report it or there are APIs available that monitor it.
So if a token has a price of $10, a circulating supply of 10,000,000, and a max supply of 100,000,000, then the Market Cap would be $100,000,000 and the FDV would be $1,000,000,000.
You can get a decent amount of the information from public dashboards like Coingecko, but digging into the details in a project’s docs can help flush out some of these subtler details like how the emissions schedule is changing over time, who the tokens are going to, and what unlocks might be happening in the future.