Estimated max fee to send 1 ETH:

We multiply the base fee by 1.125 to account for the maximum allowed 12.5% increase in the base fee between blocks. This buffer helps ensure that your transaction remains competitive even if the network congestion causes the base fee to rise unexpectedly.

The base fee is automatically determined by the network based on the demand for block space. When network activity increases, the base fee goes up to discourage congestion. When activity decreases, the base fee goes down to encourage network usage. This mechanism helps keep transaction fees at a reasonable level while ensuring network stability.