I don't get your point here. If you mean to compare the value of crypto coins to fiats, you can easily check it on exchanges or Coinmarketcap. You can see clearly the current prices of all crypto coins in dollars there. You also can check the price change history in detail on Coinmarketcap easily. But if you mean to compare the value of crypto coins and fiats as a payment tool, surely crypto coins have some limitations because they are not legal to use as payment tools in all countries. Most countries just allow them for digital assets/investments.