Michal Beno9 November 2026 · Used Miners
1Why a used Bitcoin miner is a different kind of purchase
A Bitcoin miner is a computer built for one job: running the SHA-256 math that secures the Bitcoin network. These computers are called ASICs (application-specific integrated circuits). A new one comes with a known history. A used one may have run for three years in a hot, dusty room, or been repaired with mismatched parts.
Used units are tempting because the upfront price is lower. The catch: every Bitcoin miner pays for electricity every day, and older models need more of it for the same work. So the real question is not "is it cheap?" but "what does each terahash cost to run?"
| Hashrate | How many guesses per second a Bitcoin miner makes. 1 TH/s = one trillion guesses per second. |
| J/TH | Joules per terahash: energy used for each unit of work. Lower is better. |
| Hashboard | A circuit board covered in mining chips. Most air-cooled miners have three. |
| PSU | Power supply unit. Turns wall power into the power the hashboards need. |
2The 10 checks before you pay
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1. Hashboard health Ask for a screenshot of the dashboard showing every hashboard online. A three-board miner running on two boards gives only about two-thirds of its rated hashrate. |
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2. Chip count Each hashboard should report its full chip count. Missing chips mean lower hashrate and often a board that will fail soon. |
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3. Power supply Check the PSU model matches the miner and runs without errors. A weak PSU causes random restarts. |
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4. Fans and noise All fans should spin at normal speed. A grinding fan is a sign of hard use. |
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5. Firmware Ask which firmware is installed. Unknown custom firmware can hide problems or redirect hashrate. Official firmware is the safe default. |
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6. Temperatures Chip and board temperatures should sit inside the maker's range at full load. Hot spots on one board point to dust, dried thermal paste or a failing part. |
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7. Test report A good seller gives a recent test report: hashrate over several hours, temperatures, error count. No report, no deal. |
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8. Physical condition Look for corrosion, bent heatsinks, burnt connectors and heavy dust. |
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9. Warranty Most used miners have little or no warranty left. Ask in writing what is covered and for how long. |
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10. Efficiency math Compare its J/TH against a current model at your power price, and test it against the next halving. This check decides most deals. |
3Check 10 in detail: the efficiency math
Efficiency tells you how much electricity a Bitcoin miner turns into work. The older Antminer S19 XP uses 21.5 J/TH, the Antminer S21 17.5 J/TH, and the hydro-cooled Antminer S23 Hyd 9.5 J/TH. That gap matters every day.
| 21.5 J/TH |
| 17.5 J/TH |
| 9.5 J/TH |
| Antminer S19 XP: 21.5 x 24 / 1000 | 0.516 kWh per TH per day |
| S19 XP power cost: 0.516 x 0.045 | about 2.3 cents per TH per day |
| Antminer S21: 17.5 x 24 / 1000 | 0.42 kWh, about 1.9 cents per TH per day |
| Antminer S23 Hyd: 9.5 x 24 / 1000 | 0.228 kWh, about 1.0 cent per TH per day |
| Estimated revenue (all models) | about 3.5 cents per TH per day |
The revenue figure is an estimate from public network data on 30 October 2026: BTC at about $77,600, network hashrate about 1,000 EH/s, 3.125 BTC per block plus fees. It moves daily.
4Whole-miner numbers: S19 XP vs S21 vs S23 Hyd
| 13.9 USD |
| 3.03 USD |
| 1.66 USD |
| Block subsidy after the expected April 2028 halving | 1.5625 BTC |
| Revenue per TH per day if price and hashrate stayed flat | about 1.8 cents |
| S19 XP power cost per TH per day at 4.5 cents | about 2.3 cents |
| S23 Hyd power cost per TH per day at 4.5 cents | about 1.0 cent |
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In the catalogue Antminer S23 Hyd
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In the catalogue Antminer S21
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5When a used Bitcoin miner can still make sense
Used is not always wrong. It can work when the power price is very low, the seller provides a fresh test report, and the price reflects the shorter useful life. Cheap power helps older units most.
| Daily power use: 3,032 x 24 / 1000 | 72.77 kWh |
| At 4.5 cents/kWh | about $3.27 per day |
| At 3.6 cents/kWh | about $2.62 per day |
| Estimated revenue | about $4.94 per day |
6Where to run it once you buy
Whatever you buy needs a cool, powered, watched home. See how hosting works, compare hosting locations and test models in the profitability calculator. There is also a guide to new vs used miners.
7Frequently asked questions
This article is for education only and is not financial advice. Mining revenue depends on the Bitcoin price, network difficulty, fees, power costs and uptime, all of which change. Figures are estimates based on public network data and rates listed on oneminers.com on 30 October 2026; check the live pages for current rates and prices.
