Anyone knows how transaction fees on BSV are calculated?

per byte.

Thanks, if possible, can you tell me exact formula?

$tx_fee > $size_of_tx_in_bytes * $price_per_byte_in_satoshis

Currently the default $price_per_byte_in_satoshis is `1`. If you want a discounted $tx_fee you have to talk with one of the leading miners in private.