One of the appeals of Malairte is that mining draws ordinary computer power, not industrial power. A full desktop mining all-out typically pulls 200-500 watts. A laptop is far less. This is two orders of magnitude less than a Bitcoin ASIC.
The formula is the same as for any appliance: wattage x hours x kWh price. A 350W PC running 24/7 uses about 8.4 kWh per day. At $0.12/kWh that is roughly $1 per day. Most home rigs cost a few dollars to a few tens of dollars per month, not the hundreds that an ASIC does.