Mining efficiency (J/TH)

An ASIC's spec sheet lists two key numbers: hashrate in terahashes per second and power draw in watts. Dividing watts by terahashes per second gives joules per terahash, the energy needed to perform one trillion hash calculations. It is the single most important figure for comparing machines, because electricity is the largest ongoing cost of mining.

Efficiency has improved dramatically with each chip generation. The popular Antminer S9 of 2016 used close to 100 J/TH; machines released around 2020 were in the 30s, and top models from 2023 onward dropped below 20 J/TH. Every halving, older and less efficient models fall below break-even first, so miners track the efficiency of their fleet carefully and replace the worst machines.

J/TH alone does not settle profitability. A more efficient machine can still lose money if it was bought at a high price, and an older one can stay profitable on very cheap power. Real-world efficiency also depends on cooling, overclocking or underclocking, and site conditions, so manufacturer figures are a best case.