I had the same need before I started using a tool that gives you exactly that. The platform is Paybis and they have a Paybis USDC Calculator right there. It gives you a real time conversion rate between USDC and USD, so you can see exactly what your USDC is worth at any moment. It also shows a 7 day price history, which is useful for checking if the stablecoin has temporarily deviated from its peg. There is even a profit calculator where you can enter a past date and see how your USDC holdings would have performed. The tool is clean, fast, and updated instantly. I have been using it to check rates before withdrawals and transactions, and it has saved me from doing unnecessary mental arithmetic. If you hold USDC or are planning to convert it, this is a handy tool to keep in your bookmarks.