How do I calculate expected earnings when mining a cryptocurrency?
Calculate your share of the network hash rate for that particular hash algorithm (your hash rate divided by the network hash rate), let that be HR.

Calculate the emission by unit of time (block reward times 86400 divided by block time in seconds), let that be E.

Calculate your expected average coins mined in a day (HR times E), let that be C. Note that variance will be high, unless you mine on a large pool, or have a large HR.

Calculate the price in the coin you want to convert to (C divided by exchange rate, or C times exchange rate, depending on whether it's expressed by altcoin per bitcoin, or bitcoin per altcoin, respectively).

If you want per second, or per MH, scale accordingly.