ShapeShift does not charge any specific fees outside of the miner fee. Instead, we offer an exchange rate for each coin which changes every thirty seconds dependent on market conditions. We try to earn revenue by offering a profitable exchange rate, and typically we earn in the range of 0.5% (50 basis points). You receive exactly what the exchange rate shows, there is no additional fee for the service.
This is how you would calculate the instant rate in this particular transaction on ShapeShift.io:
The Rate posted is 1 BTC = 40.85042657 ETH. You would calculate the amount you would receive by taking the amount of bitcoin you plan on depositing- let's say for this example we are depositing .5 BTC- and multiplying it by 40.85042657 Ether.
.5 x 40.85042657= 20.42521328
The only fee that would be removed after doing this calculation is the Ether miner fee. You can see this in the above image on the right-hand side posted as 0.0013 ETH.
To conclude, the final amount of Ether you would receive would be:
.5 x 40.85042657= 20.42521328 - 0.0013= 20.42391328 ETH
If you are using our new ShapeShift.com/Trade platform, you will see the rates to the right hand side of the trade. This includes the breakdown of your "Free Trading" with FOX. Below your rate you will see how much more of your desired asset you were able to receive by using FOX. To be eligible for the "Free Rate" you need to hold FOX in your active wallet account. 
If you don't have any FOX in your active wallet you will notice a section below your rate where the Platform will display how much more of your desired asset you would have received if you had used FOX. By FOX eliminating any additional trading costs you will notice that you are getting the best rates possible!
Learn how to earn 10 FOX to your account today (that's $100 worth of free trading each month!).