How do we calculate the total number of bytes in a transaction we have done?
Most of the bitcoin wallets have fee recommendation system which will tell you how much fee will be enough to get confirmation within next block.
But if you like to calculate manually
http://bitcoin.stackexchange.com/questions/1195/how-to-calculate-transaction-size-before-sendingIf your transaction has in inputs and out outputs, the transaction size, in bytes will be:
in*180 + out*34 + 10 plus or minus 'in'
For example, this transaction has 40 inputs and 16 outputs. That gives us a transaction size of
40*180 + 16*34 + 10 +- 40
i.e. 7754 +- 40 bytes. The actual size is 7761 bytes.
I think this is correct calculation.
Where did the -40 come from during the calculation? Why-16 not used? What's the use of -40?