The more the inputs and outputs, the more the fee. The second output will likely be the change address (the address you will receive your change). The difference in the fee will be minimal.
The output is the number of addresses that you are sending to. If your coin has change, it would be sent to the change address.
I can't understand the part that is in bold. I'm confused, sorry.
Bitcoin isn't stored as just a "sum" number like cash in your bank account... it's stored in "chunks" called UTXO's (Unspent Transaction Outputs). So, every time you receive some Bitcoin, you get another chunk added to your collection. When you want to send someone some Bitcoin, unless you have a chunk that is
exactly the right size to cover the amount you're sending + fee, then there will be leftovers... this is called "change" and is simply put back in your wallet as a new (smaller) chunk.
Let's say you have chunks worth 0.1, 0.2 and 0.3 BTC... you decide you need to send 0.15 to someone. You don't have a chunk that is exactly 0.15... so your wallet will use either the 0.2 or 0.3 chunk (depending on what sort of UTXO selection algorithm your wallet uses).
Let's assume your wallet uses the 0.2 chunk. Your wallet will create the transaction and says please send 0.15 to AddressA... and put the remaining 0.5 back in my ChangeAddressY (we'll ignore fees for now).
More reading here:
https://en.bitcoin.it/wiki/Changeand here:
https://en.bitcoin.it/wiki/Coin_analogyBasically, unless you spend the exact amount of some combination of chunks, you're most likely going to have 1 extra output on any given transaction (which is simply the "change" going back to your wallet).
Note: The number of
Outputs has a very minimal effect on the data size of a transaction compared with the number of
Inputs which will have a much greater impact on the data size of transaction (and hence will affect the total fee more).
The reason for this is that an Input typically has 2-3 times the data size of an output. For instance, with transactions using older bitcoin addresses (P2PKH) an input would be around 148 bytes... and an output would be about 34 bytes. Newer addresses are slightly less.
Unless you're sending to multiple people in 1 transaction (like an exchange doing a batched send), chances are that the data size of your inputs is going to be far greater than the data size of your outputs.
This is why receiving a lot of small BTC amounts ends up costing a lot in fees to move... if you have 10x chunks of 0.01... and you want to send 0.1 BTC, you suddenly have 10 inputs and your transaction data size is going to be quite large and require a very large fee.
-snip
If you want your transaction to include only 1 output, you should spend the entire balance of selected UTXOs, so that your transaction doesn't have any change.
So what I need to do is just send the maximum amount of the current multi-signature wallet to a standard wallet, right?
Thanks again for the help.
Correct, send the maximum amount in 1 transaction. If you use the max button in Electrum (or set the amount value to ! ) it will automatically calculate that "max" value for you based on the total amount in your wallet - minus the transaction fee.