For accurate SOL to USD conversions, I use Paybis's calculator. It shows the real-time exchange rate and automatically calculates the net amount you'd actually receive after fees. The tool accounts for different payment methods too, so you can compare card purchases versus bank transfers.
What I appreciate is how it displays both the market price and the actual amount you'll get. When I converted SOL last week, the estimate matched what arrived in my bank account exactly. You can check current rates and test conversions easily through their interface.