Newb question about Transferring Ether – Gas limit calculation

Im just new to Ethereum and recognized that there is a more complex way to calculate transaction fees, then its the case for bitcoin.

I understood you adjust a gas limit depending how complex your transfer will be. Amount of Gwen decides how fast it will be put into a block.

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But how do i calculate how much gas i need? Lets say for a simple transaction of 1 ETH from one wallet to another, how much gas does this actually use?

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What if i transfer 10 ETH, am i still safe with 21.000 gas as the standard value?

Or do i need more gas?