Nothing guaranteed, of course this is only a rough estimate!
Do not enter commas, only dots for decimal separator. You can also calculate rented mining by setting “Power consumption” to 0 and “Cost of mining hardware” to the rent per time frame. Default values are for a system of four 6870s.

Estimate Strategy

Extrapolating bitcoin difficulty or price is pure voodoo. It is much easier to predict the relationship of the two parameters in form of the Mining Factor. The Mining Factor 100 is the value in USD of the bitcoins you can generate if you let a 100MHash/s miner run for 24 hours. If the Mining Factor 100 rises above $2 or so everybody buys mining equipment and thus increases difficulty. If it falls people will stop mining eventually. The estimate starts with the current Mining Factor and decreases it exponentially such that the decrease accounts for the factor decline per year. Please note that a profit/loss by holding the coins is not accounted for in this estimate.

Things to consider that might eat into your profit:

Possible additional benefits: