Hidden fees in a transaction: How to anticipate one and avoid another?

Question

On Bitcoin.org, the page on getting started has a button for "Buy Bitcoin". It links to page with a dialog box that appears to be an interface to the service, MoonPay. MoonPay has a page, "What fees do you charge?" From that page and other analysis (described below), I infer that there are at least three fees incurred in a transaction:

• Processing fee of either 1% or 4.5% for depositing or withdrawing fiat currency, depending on how the transfer is done. (Strangely, the fees page seems to indicate that withdrawals can only be made to a bank in the EU or UK, which could be a problem for people living elsewhere.)

• Dynamic network fee, which is apparently calculated when a transaction is proposed. Nothing is said about how much it might be. Is there a way to know what amount of fee one should anticipate? I have seen block data for a transaction in which the transaction amount was 0.00130696 BTC and the fee was 0.00125343 BTC, or 95% of the transaction amount. Why would anyone ever make a transaction in which the fee is almost equal to the amount of the transaction?

• Currency spread, or premium. I compared the exchange rate shown on Bitcoin.org to that shown by Google in the same second:

The difference shows a spread of 35,026.27 / 33,935.1 = 1.032. This indicates that there is a price premium of at least 3% built into the exchange rate used on Bitcoin.org. This premium is like the premium charged by banks for conversion of fiat currencies. It is a hidden fee that both banks and MoonPay don't state in their fee schedules. I figure this is how the crypto exchanges make most of their money.

So my two questions are:

• I understand that the "dynamic network fee" is part of the process of operating the blockchain and cannot be avoided. But how can I anticipate in advance how much to expect this fee to be?

• I've read that it's possible to transact bitcoin without using an exchange, and I suppose this would eliminate the price premium. What does one have to do in order to transact without an exchange?

Answer 1

I understand that the "dynamic network fee" is part of the process of operating the blockchain and cannot be avoided. But how can I anticipate in advance how much to expect this fee to be?

Without knowing how the exchange operates their wallet internally, this is unpredictable. Many exchanges will display an estimate for the transaction fee, but the transaction fee itself all depends on how they work. The transaction fee is not based on the amount being transacted; rather it is based on the size in bytes of the transaction itself. This size cannot be known without knowing how the exchange is creating their transactions.

I've read that it's possible to transact bitcoin without using an exchange, and I suppose this would eliminate the price premium. What does one have to do in order to transact without an exchange?

You simply download and install a Bitcoin wallet software and use it to receive and send Bitcoin. The wallet software will allow you to create Bitcoin addresses which you can give out in order to receive Bitcoin. It will also allow you to send Bitcoin to addresses that you have received from others. Bitcoin.org has a page which lists out some wallet software that you can download.