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Field report · Sep 21, 2026 · 6 min read
What 910 days on an Antminer S21 actually produced
0.087 BTC, $2,732 of electricity, and a machine that still returns 46% in its first year at today’s price. 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 $3,957 and landed at $6,142 in Argentina, running at 6¢ since March 2024. Across 910 days it has mined and kept 0.0866 BTC, worth about $7,041 today, for $2,732 of electricity — $31,530 a coin.
Cashflow of $4,310, 70% of its landed cost, with another 0.041 BTC and about $3,641 in it before the 2028 halving. On those figures it lands near 1.3× its hardware by April 2028 and keeps running afterwards.
It ran 159 days in Argentina and moved to Nigeria on 31 August 2024, where it has been ever since. That move was not a rescue — it was still clearing comfortably at 6¢. Nigeria simply started paying better, so it went.
It never needed rescuing. It moved because Nigeria started paying better, 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 46% 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.
- Bitmain Antminer S21 XP (270 TH/s) — 13.5 J/TH, In stock, $42,484 of electricity per bitcoin, 38% year one
- Bitmain Antminer S23 (318 TH/s) — 11 J/TH, Pre-order, $34,617 of electricity per bitcoin, 32% year one
- Bitdeer SealMiner A4 Pro Air (336 TH/s) — 10.9 J/TH, To be released, $34,298 of electricity per bitcoin, 50% 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.