You enter the amount of ETH you wish and it will estimate how much it would cost. Alternatively you are able to enter the level of fiat you should expend. The platform will calculate how much ETH you will get. Learn far more about the denomination of Ethereum units. https://financefeeds.com/best-copyright-presales-to-invest-in-analyst-says-this-solana-layer-2-project-will-explode/