For essentially the most half, your pockets software program ought to handle all this. It is best to solely decide how urgently you want the transaction to be confirmed and decide the feerate, the pockets would handle the remainder. The 88 you point out would seemingly consult with a feerate of 88 sats/vbyte right here, though that seems like a gross overestimate on the present market circumstances.
If you wish to manually construct a transaction, you have to know a bit extra.
Earlier than you construct a bitcoin transaction, you understand which transaction outputs you’re aiming to create. The recipients addresses inform you how a lot information it’s going to take to specify every output within the transaction. The transaction header can be principally fixed dimension, it is 10 bytes for non-segwit transactions and 42 weight items for segwit transactions.
The enter aspect is a little more difficult, as you often have no idea upfront what number of inputs it’s going to take to fund your transaction. Your pockets might also be capable of spend Unspent Transaction Outputs (UTXOs) of assorted output varieties which take completely different quantities of information to incorporate in a transaction.
So, you may both want to select the inputs first, then decide their dimension and calculate the charges, or you are able to do each in live performance, by calculating the price for every enter and deducting in from the UTXO’s values earlier than contemplating them for inclusion.
The precise sizes for some well-liked output varieties might be seen on this desk: 