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Field report · Sep 7, 2026 · 6 min read
What two and a half years on an Antminer S21 actually produced
Bought once its price settled, moved to cheaper power the moment that paid better, and still clearing comfortably today. The S21 is the closest thing this industry has to a boring machine, and that turned out to be the point.
Bitmain Antminer S21 (200 TH/s)
The tally
A 200 TH/s S21 bought at $4,032 once its price settled and landed at $5,590 in Argentina in February 2024. Across 994 days it has mined and kept 0.1208 BTC, worth about $9,343 today, for $4,979 of electricity — $41,222 a coin.
Cashflow of $4,363, 78% of its landed cost, with another 0.033 BTC and about $4,154 in it before the 2028 halving. On those figures it lands near 1.5× its hardware by April 2028 and keeps running afterwards.
It ran 915 days in Argentina and moved to Nigeria on 19 August 2026, where it will stay. That move was not a rescue — it was still clearing comfortably at 6¢. A year of figures had simply made Nigeria the better home for it, so it went.
It never needed rescuing. It moved because cheap power had become the better home for it, which is a different thing entirely.
17.5 J/TH turned out to be the sweet spot
The S21 arrived at a strange moment: eight months before the halving, priced above the S19K Pro and below the XP models, at an efficiency that looked unremarkable next to both. It was the machine you bought when you did not want to make a call.
That non-call aged well. 17.5 J/TH was efficient enough to survive April 2024 without the cliff the 23 J/TH machines went over, and cheap enough that its payback was never in doubt. The machines either side of it — thirstier and cheaper, or leaner and far more expensive — both had sharper outcomes in one direction or the other.
At today’s rates it still returns about 22% in year one at our Argentina site, which is a remarkable thing for a machine announced in August 2023 to be able to say.
Where it stands now
The 200 TH/s variant is sold out; the 151 TH/s bin is still in stock and priced accordingly. At 17.5 J/TH it clears comfortably at 6¢ today and has a long life ahead at 3.9¢ once it stops doing so, which on current trends is some years away rather than some months.
If you are buying today there are better machines — the S21 Pro makes a cheaper coin for less money, and the XP makes a cheaper coin still. But the S21 is the reference point for what a well-judged purchase looks like: unremarkable specification, sensible price, no drama, paid for itself.
- MicroBT Whatsminer M74S+ (332 TH/s) — 12 J/TH, In stock, $42,565 of electricity per bitcoin, 24% year one
- MicroBT Whatsminer M73S (560 TH/s) — 13 J/TH, In stock, $46,113 of electricity per bitcoin, 27% year one
- MicroBT Whatsminer M70S (260 TH/s) — 13.5 J/TH, In stock, $47,886 of electricity per bitcoin, 23% year one
Which machines this covers
Disclosure
Firsthand Bitcoin sells and hosts mining hardware, including this machine. No manufacturer, distributor or affiliate programme paid for or reviewed this page and we take no commission on the links above. Historical figures are computed from daily bitcoin price and network hashprice, each day valued at its own prices. Nothing here is investment advice.