Gas fee

A gas fee is what you pay to get a transaction processed on a blockchain such as Ethereum. The computers running the network do real work to execute and record your transaction, and the gas fee is what compensates them for it. No fee, no processing.

"Gas" measures how much computation an action needs. Sending coins is cheap because it is light work. Running a complex smart contract costs more gas because it asks the network to do more. Your fee is the gas used multiplied by the price per unit at that moment.

That price is not fixed. It rises and falls with demand. When lots of people want their transactions confirmed at once, they bid the price up to jump the queue, and fees spike. During quiet hours the same transaction can cost a fraction as much. Timing matters.

This catches newcomers out. The fee has nothing to do with how much you are sending. Moving a few pounds of cryptocurrency during a busy spell can cost more in gas than the amount itself. On a congested day, a single Ethereum transaction has at times cost more than 50 pounds.

Gas is paid in the network's own coin, ether on Ethereum, so you always need a little spare to cover it. Other blockchain networks charge their own fees under different names, and many run far cheaper than Ethereum by design. Banxa lets people buy crypto, including the ether needed for gas, through a regulated on-ramp.