To estimate a fee, we need a way to relate the number of transaction inputs (in) and outputs (out) to it's size in bytes (size). The exact size of a transaction can only be determined after it has been signed, which is unfortunately too late to be of much use in many wallet programs. However, the upper size limit can be
found with this equation:
size = 181 * in + 34 * out + 10
Your information is also out of date. The equation you posted is out of date, it uses uncompressed key which is not what most wallets implement right now. Compressed keys uses this equation
134byte*/input+ 32byte/output*