That's a great starting point! I use this really handy converter that shows you exactly what you'd get. For your specific question, check out this 100 usd to btc calculator - it gives you the real-time conversion rate and shows the exact Bitcoin amount you'd receive, including any platform fees. What's cool is it updates live as the market moves, so you always see the current rate. I use it all the time before making purchases to know exactly what I'm getting.