I am new in mining Ethereum. I mine with ethminer on Ubuntu 15.04 server edition at ethereumpool.co with msi r9 280x graphic card which is in x16 slot. During mining I notice that I get info about mining with 19-20 Mhs. However on https://badmofo.github.io/ethereum-mining-calculator/
when I put 20 Mhs I get result like I should mine 0.28 per day. In reality I get only 0.24 per day. ethminer -G -M show to me average of 22 Mhs not 20 so I guess I should get more than 20 during mining. Question is is this mining calculator wrong or is this some ethereumpool mining pool problem or is it some option like that I should put 26 in ethminer command instead of just 22 ?
Thank you in advance