A Bitmain Antminer S19j Pro at its top bin of 104 TH/s grosses £2.55 a day on today’s difficulty. It draws 3,068 watts to do it — 73.63 kilowatt hours. So it needs electricity at 3.46p per kWh to cover its own power.
The cheapest half-hour on Octopus Agile in Eastern England today was 34.99p. That is roughly ten times the break-even price, in the single cheapest slot of the day.
No UK retail tariff makes this machine work. At the Ofgem cap unit rate of 26.32p it loses £16.83 a day, or £6,143 a year. On Agile’s median of 37.045p it loses £24.73 a day, £9,025 a year. Bitcoin would have to reach £441,809 — 7.6 times today’s £58,142 — before the machine broke even at the cap.
The specification, from Bitmain rather than a reseller
Bitmain’s own documentation gives six bins, all at 29.5 J/TH: 104 TH/s at 3,068 W down to 84 TH/s at 2,478 W. The useful part for a UK buyer is the input, 200 to 240 volts at 47 to 63 Hz — single-phase, well inside UK domestic supply. That makes it genuinely different from the hydro and three-phase machines reviewed here recently, which cannot go in a house at all.
It still cannot go on a plug. At 3,068 W the draw is 13.34 A at 230 V, above a BS 1363 plug’s 13 A rating, and Bitmain’s own note settles it: “Two AC input wires, 10A per wire”. The supply has two inlets and wants two outlets. The right answer is a dedicated radial on a 16 or 20 A breaker, sized to the supply’s 20 A rating, not the running draw.
Age is the real risk
Bitmain announced the S19j Pro in November 2020 and shipped it from June 2021, in monthly batches running about a year. The launch post promised a “life cycle… expected to exceed 5 years”. That window has closed.
Warranty on a 19-series miner is 365 days from shipment, so cover on every S19j Pro ever made expired by roughly mid-2023. Bitmain’s extended-warranty product, on sale this quarter, lists only S21 and S23 models, so there is no price at which cover can be bought. The machine is not on the end-of-service list, so paid repair is nominally possible — but there is no UK repair centre. A UK owner ships to Amsterdam, Dubai or Hong Kong at their own cost, as an export then a re-import.
A replacement power supply is $229, about £171. One vendor sells the whole machine for $299, about £223.
Pricing gives the market away. One vendor lists the 104 TH bin at $299 and the lower 100 TH bin at $1,399 — $2.88 against $13.99 per terahash, both in stock, both claiming a 365-day warranty that cannot be Bitmain’s. Of more than ten listings, two stated the condition of the goods at all. An explicitly used Hong Kong unit at $448 costs more than the $299 one whose condition is blank, which tells you what the blank means. These are list prices with no VAT basis stated; UK import VAT at 20 per cent applies on top, though duty on the relevant heading is nil.
| Gross revenue | £2.55 a day |
| Power drawn | 73.63 kWh a day |
| Break-even power price | 3.46p per kWh |
| Ofgem cap unit rate, to 31 Dec | 26.32p — loses £16.83 a day |
| Agile cheapest half-hour today | 34.99p — loses £23.21 a day |
| Agile median today | 37.045p — loses £24.73 a day |
| Against the current air-cooled S21 XP | 29.5 against 13.5 J/TH |
| Revenue per megawatt | £831 a day |
The case for buying one anyway is narrow but real. It is single-phase and air-cooled, so it needs no plant room, no glycol loop, no three-phase application. At $299 the downside is a few hundred pounds. If you have genuinely free or curtailed power — surplus solar that would otherwise be clipped — 3.46p is a low bar, and it is the cheapest way to learn on a real miner.
The case against is everything else: no warranty, no UK repair route, a power supply costing 77 per cent of the machine, 75 dB of continuous noise and 10,468 BTU an hour to get rid of. Note too that the current-generation S21 XP breaks even at 7.57p and also loses money on every tariff above. This is not an argument for a newer machine. On Eastern England retail power today, it is an argument against the activity.
Difficulty, block reward including fees and the next retarget from mempool.space; Bitcoin at £58,142 from CoinGecko; both at 13:43 UTC on 2 November 2026. Hashprice derived here as 144 × 3.14213764 BTC × price ÷ 1,062.03 EH/s net of a 1 per cent pool fee, and every figure computed from it, not from a calculator. Octopus Agile, tariff E-1R-AGILE-24-10-01-A, Eastern England: 46 of 48 half-hours were published, so the median and mean are of 46, and inclusive and exclusive VAT values were identical in every slot — consistent with Ofgem’s statement that VAT was removed from electricity bills from 1 October 2026 to 31 March 2027. The 26.32p cap rate is the national average to 31 December, not regional. Specifications, warranty and repair addresses from Bitmain’s own support documentation, fetched the same afternoon. Contested: Bitmain gives 2,950 W for the 100 TH bin where four secondary sources give 3,050 W, inside its own ±5% tolerance; one vendor advertises a 90 TH bin Bitmain does not publish; the 75 dB figure is from aggregators, as Bitmain states none; the 1.3399 dollar rate is three days stale. Prices are ex-VAT. Not a recommendation to buy, sell or hold anything, and not electrical advice.