Quote from: hosseinimr93 on Today at 09:39:58 AM

With sending from segwit addresses, you decrease the transaction fee, because your transaction would include some witness data that are not counted when calculating the transaction fee.

They are counted. Witness data is counted as one quarter the size of regular data.

The calculation is defined in BIP 141. To calculate the transaction weight, you take the base size of the transaction without the witness data, multiply it by 3, and then add the total size of the transaction with the witness data included. This means that the witness data is only counted once, while non-witness data is counted four times. This gives you the transaction weight in weight units, which you divide by 4 to get the virtual size in vbytes.

In effect, this means that for non-witness data there is a 1-to-1 correlation between bytes and vbytes, while for witness data, it is 1 byte to 0.25 vbytes.