While trading low-priced coins, you may see something like this: estimated fee greatly exceeds the declared 0.1%. Take a look at the picture: the displayed fee makes up to 10% of the order amount. Why is that so?
Of course, you won't pay that much. What you see is the worst-case scenario, which is highly unlikely to happen in real life, but the Bitcoin.com engine has to consider it and display it to you. More on that below.
In every trade on the exchange, one of the participants (takers) is paying the 0.1% fee. But if the trade amount is very low and the coin is very cheap, the 0.1% fee can become incalculable, less than a satoshi. In that case, the fee amount is rounded up to the nearest calculable amount.
Hypothetically, your order could be filled with a huge amount of low-volume trades. For every such trade, you pay slightly more than 0.1%, and the total fee amount grows really big. This is the worst-case scenario, which our engine takes into consideration while counting up the fee amount.
What happens in real life then?
As you create your order, the displayed fee amount is locked on your account balance. It is used to pay the fees when necessary. Once your order is filled or canceled, the unspent amount is just unlocked, so you can use it again.
So what you really pay does not excess 0.1% of the order amount. The frightening fee amount displayed is just a boundary effect, happening when trading very low-priced coins.