Network fee is required to make transaction confirmation in the blockchain. These funds go to miners who approves your transactions. If the blockchain works on the consensus other than proof-of-work, or the proof-of-stake, the commission is needed for the system to avoid spamming or overloading of the blockchain.
How to Calculate fees
For now, you need to plus additional 0.00001 ZEC to your Amount to know the certain price that will be withdrawn from your Balance.
In this case, you need to have at least 0.00081 at your ZCASH balance to make a successful transaction.
You should also pay attention to your actual balance. Point your mouse on the balance near ZCASH. As you can see, I have 0.007918 instead of 0.007919 ZEC on my balance. Check it out before making transactions.
Let's proceed to the Exchange tab.
These fees are calculated by exchange services, in Atomic Wallet we support Changelly and Shapeshift.
And there is also a minimum amount requirement.