An ASIC (application-specific integrated circuit) miner is a machine whose chips can run only one hashing algorithm. For Bitcoin that algorithm is SHA-256. Because the chip does nothing else, it computes far more hashes per watt than a CPU or graphics card. That is why proof-of-work networks like Bitcoin are now mined almost entirely with ASICs. The figure that matters most is efficiency, measured in joules per terahash (J/TH). Bitmain's hydro-cooled Antminer S23 Hyd is rated at 9.5 J/TH. The S19 Pro, a flagship a few generations ago, was rated at 29.5 J/TH.
How an ASIC miner works
Bitcoin's developer documentation describes the process. Mining software builds an 80-byte block header and sends it, along with a target threshold, to the mining hardware, "an ASIC". The chip tries nonce values until it finds a header hash that falls below the target. If it runs through every nonce without success, the software changes the extra nonce in the generation transaction and the search starts again.
Two protocol rules shape the economics:
- Difficulty adjusts every 2,016 blocks. If those blocks arrived in less than two weeks, difficulty rises. If they took longer, it falls. More machines on the network do not mean more bitcoin per day for the network as a whole. They mean each machine's share gets smaller.
- The block subsidy halves every 210,000 blocks. The fourth halving came at block 840,000 on 20 April 2024 and cut the subsidy from 6.25 BTC to 3.125 BTC. For the same hashrate share, a machine now earns roughly half the subsidy it earned before that block.
Each ASIC fits one algorithm only. A SHA-256 machine cannot mine a Scrypt coin, and a Scrypt machine cannot mine a SHA-256 coin.
Which coins ASICs mine
| Algorithm | Main coins | Note |
|---|---|---|
| SHA-256 | Bitcoin | Mining uses SHA-256 as the proof-of-work algorithm |
| Scrypt | Litecoin, Dogecoin | Dogecoin added auxiliary proof-of-work (AuxPoW), so Litecoin miners can merge-mine it |
| Ethash | Ethereum (historical) | Obsolete for Ethereum: since the Merge on 15 September 2022, "mining is no longer the means of producing valid blocks" |
The old advice to mine Ethereum with ASICs no longer applies. Ethereum moved to proof-of-stake, and validators now propose blocks.
Efficiency by generation: Bitmain Antminer models
| Model | Hashrate | Efficiency | Released |
|---|---|---|---|
| Antminer S19 Pro | 110 TH/s (±3%) | 29.5 J/TH (±5%) | earlier generation |
| Antminer S21 | 200 TH/s | 17.5 J/TH | 2023–24 |
| Antminer S21 Pro | up to 245 TH/s | 15.0 J/TH | 2024 |
| Antminer S21 XP (air-cooled) | 270 TH/s | 13.5 J/TH | 17 June 2024 |
| Antminer S21 XP Hyd (hydro-cooled) | 473 TH/s | 12.0 J/TH | announced June 2024 |
| Antminer S23 Hyd (hydro-cooled) | 580 TH/s | 9.5 J/TH | May 2025 |
The S19 Pro figures come from Bitmain's support page. The S21-series figures come from Hashrate Index's hardware overview and rig database. The S23 Hyd figures come from Bitmain's shop listing and Hashrate Index.
At 9.5 J/TH, a machine uses about a third of the energy per terahash that the S19 Pro needs at 29.5 J/TH. Two machines can produce the same number of hashes, but the less efficient one pays about three times as much for the power. That is why older units are often the first to be switched off after a halving or a rise in difficulty.
"Hyd" models use liquid cooling and need water loops, pumps and heat exchangers. Air-cooled models need strong airflow and are loud. Noise levels vary by model, so check the spec sheet for the exact unit.
Bitmain is not the only maker. Canaan says its founding team shipped the first batch of ASIC Bitcoin miners in 2013 under the Avalon brand, before Bitmain's Antminer line became dominant.
What does your ASIC cost to power each day?
Enter your machine's rated power, your electricity price and any cooling overhead to see the daily power bill.
| Rated power draw of your machine | Your electricity price | Extra power for cooling and other overhead | Daily power cost |
|---|---|---|---|
| 3.25 kW | 0.08 per kWh | 0 % | 6.24 per day |
| 3.645 kW | 0.08 per kWh | 0 % | 7 per day |
| 5.51 kW | 0.08 per kWh | 10 % | 11.64 per day |
- The price and overhead values are your own inputs, not figures from any source.
- Rated power is a manufacturer figure with stated tolerances; real draw can differ.
This covers only electricity: it leaves out mining revenue, which moves with difficulty, the BTC price, transaction fees and pool fees, as well as purchase, shipping, electrical work and maintenance costs.
Running costs: the arithmetic
To get daily power use, multiply the rated power by 24 hours:
- S19 Pro: 3.25 kW × 24 h = 78 kWh per day
- S21 XP: 3.645 kW × 24 h ≈ 87.5 kWh per day
- S23 Hyd: 5.51 kW × 24 h ≈ 132 kWh per day
Multiply that by your electricity price per kWh, including cooling overhead, to get the daily cost. Revenue depends on factors that move every day: network difficulty, the BTC price, transaction fees and your pool's fee. Any estimate that combines them is a snapshot, not a forecast. A difficulty adjustment or price move changes the result within two weeks. The next halving, expected about four years after April 2024, cuts the subsidy again.
Other costs to include:
- Purchase price, which varies widely between sellers and over time
- Shipping and import duties
- Electrical work: these machines run on 200–240 V AC
- Cooling infrastructure for hydro models
- Space and maintenance
- The local legality of mining and any grid restrictions
Solo mining or a pool
A solo miner keeps the full block reward and fees but gets large, infrequent payouts. For a single machine against today's network hashrate, finding a block could take years. In a pool, miners combine hashrate and share the proceeds in proportion to their work, so payouts are smaller and more regular.
Pools set a target that is easier than the network's, so each machine submits frequent proofs called shares. Bitcoin's documentation explains: "The information the miner sends to the pool is called a share because it proves the miner did a share of the work." Most pools connect miners over the Stratum protocol, which sends the data needed to build headers over a persistent connection. Under standard Stratum, the pool chooses which transactions go into a block.
Payout schemes
- PPS (pay per share): each valid share is worth a set amount, whether or not the pool finds a block.
- FPPS (full pay per share): like PPS, but it pays out part of the transaction fees as well as the subsidy.
- PPLNS (pay per last N shares): pays from blocks the pool actually finds, based on the last N shares. The miner carries more variance, and fees are usually lower.
Before you join, compare the pool's fee, minimum payout threshold, payout frequency and server latency from your location. If the minimum payout is high, small miners wait longer to be paid.
ASIC vs GPU
GPUs can switch between algorithms, and they keep a resale value outside mining. ASICs cannot switch, but on their one algorithm they are far more efficient. For SHA-256 and Scrypt, GPU mining cannot compete with ASICs on cost per hash. For Ethereum, the Merge ended GPU mining entirely.
Main risks
- Obsolescence: each new generation lowers the J/TH rating, and difficulty rises as new machines are plugged in.
- Revenue swings: income depends on the coin's price and on fees, and both are volatile.
- Halvings: each one roughly halves the subsidy at the same hashrate share.
- Pool and seller fraud: check a pool's payout history and buy through traceable channels.
The hashrate and J/TH figures above are rated values. Individual units can differ within the stated tolerances.
