There is no universal fixed cost to mining bitcoin, but there are several key variables that every miner uses to estimate their operating costs.
Probably the most important cost to any miner is the cost of electricity they use to power their operations. Cheap electricity lowers a miner’s operating costs. When looking to build a mining farm or host machines at an existing facility, miners prioritize cheap energy to lower their operating costs and boost their profit margin.
All mining machines aren’t created equal. Different models operate at different levels of efficiency, which is typically measured in Joules per terahash (J/T). ASICs with a lower J/T efficiency generate more hashes per Joule of energy consumed.
Because mining is essentially a race of hashing, miners with more efficient machines and larger numbers of machines have higher probabilities of solving each block and claiming its reward.
Included in the mining cost calculation are other variable costs, like hardware maintenance, insurance or warranties, and tax liabilities. Also, for miners who contribute their hashrate to a mining pool, pool fees – the percentage of mined BTC that is kept by the pool operators – are an additional cost that should be included in the overall calculation.