All transactions that take place over the Bitcoin network require a miner fee to be attached in order to incentivize the network to process the transaction. Since the network can only process a limited number of transactions per second, transactions with a higher miner fee are prioritized over those with a lower miner fee.
Recently, the Bitcoin network has been experiencing congestion which has increased the time it takes for a transaction to be confirmed as valid by the network. This can cause wait times of hours or even days for transactions without a sufficient miner fee attached. This does not create a very good user experience.
To avoid this, ShapeShift uses a flat miner fee of 0.0021 BTC for every Bitcoin transaction we facilitate regardless of the size of the transaction. This relatively high miner fee ensures that our users are able to receive their funds as quickly as possible without experiencing delays due to network congestion.
This can disproportionately impact smaller value transactions. For example, if you attempt to deposit 0.007 BTC to ShapeShift for an exchange but the timer has expired and the funds are returned to you, you will be refunded 0.007-0.0021=0.0049 BTC. Likewise, if you are expecting an output from ShapeShift of 0.007 BTC after a successful exchange, you will also receive 0.007-0.0021=0.0049 BTC. While this might seem drastic, ShapeShift does not profit off of this miner fee in any way and it is necessary to minimize delays experienced by our users.