ASIC Efficiency expresses the energy needed to calculate a given number of hashes. Bitcoin mining commonly uses J/TH; this is computation’s energy intensity, not a power supply’s efficiency percentage or a profit metric.
Input power in W divided by Hashrate in TH/s gives J/TH, because a watt is a joule per second. An illustrative 4000 W at 200 TH/s therefore means 20 J/TH. A lower value uses less energy for the same number of hashes. [BITMAIN — S21 Pro specification (2024)]
The 2024 S21 Pro specification lists 234 TH/s, 3510 W and 15 J/TH at an inlet air temperature of 25 °C. These are typical values with stated tolerances, not a guarantee that every unit matches them at any temperature. [BITMAIN — S21 Pro specification (2024)]
Measurement at a machine’s electrical input includes what that input supplies. It differs from an estimate for chips alone; separate pumps or facility cooling must be added separately. Braiins expressly recommends actual measurement rather than relying on software estimates. [Braiins Academy — DPS and autotuning FAQ]
Braiins describes chip differences and temperature effects on tuning and power draw. Record temperature, mode, firmware and a matching measurement period for comparisons; startup data does not automatically represent steady operation. [Braiins Academy — Autotuning]
Autotuning finds suitable voltage and frequency for individual chips. Overclocking raises hashrate but can worsen J/TH. Assess input power and hashrate together, rather than just the configured limit. [Braiins Academy — DPS and autotuning FAQ]
An illustrative change from 200 TH/s at 4000 W to 150 TH/s at 2700 W improves the metric from 20 to 18 J/TH. Energy per hash falls 10%, but hashrate also falls by a quarter; this is no recommended setting for a particular machine. [Braiins Academy — DPS and autotuning FAQ]
Sum machine power draws and hashrates measured under comparable conditions, then divide. An illustrative 200 TH/s at 4000 W plus 100 TH/s at 3000 W gives 7000/300, about 23.33 J/TH, not the simple average of 25 J/TH. [BITMAIN — S21 Pro specification (2024)]
Results also depend on Hashprice, electricity price, uptime, fees and investment. Saving energy per hash does not automatically reduce total consumption: adding machines or increasing hashrate can raise total power draw. [Braiins — Mining profitability inputs]
For the clearest picture, read this entry together with ASIC Miner, Hashprice, Joules per Terahash, Autotuning. The reverse links also lead from Hashprice, Joules per Terahash, Autotuning, Underclocking.