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Progress report · Sep 21, 2026 · 5 min read
Eighteen months with the Antminer S21+, and where it goes next
0.048 BTC banked, a third of its hardware covered, and the best entry price it has ever had. Here is what it has done so far and what the next two years look like.
Bitmain Antminer S21+ (225 TH/s)
What it has done so far
A 225 TH/s S21+ at 16.5 J/TH, bought at $3,229 and landed at $5,159 in Argentina, running at 6¢ since April 2025. In 530 days it has mined and kept 0.0478 BTC, worth about $3,883 today, for $2,083 of electricity — about $43,600 a coin.
That is $1,800 of cashflow and roughly 35% of its landed cost — about where a machine should be eighteen months into a four-year working life. It ran 231 days in Argentina and moved to Nigeria on 26 November 2025, not because it stopped clearing at 6¢ but because Nigeria began paying better.
The next two years
At today’s difficulty and with bitcoin back at its previous high, the S21+ has another 0.046 BTC and roughly $4,189 in it between now and April 2028. Added to what it has already banked, that puts it near 1.16× its full landed cost by the halving — hardware, freight, duty, customs and setup all covered, with the machine still running.
And it will still be running. At 16.5 J/TH it clears comfortably at 6¢ today and will still clear at 3.9¢ well past 2028, which is the test most hardware fails. Our Nigeria site is where that second act happens, and it is measured in years rather than months.
The hard part is behind it. Everything from here is the flatter, longer half of the curve.
The entry price does the work
A buyer today gets the same 225 TH/s at 16.5 J/TH for about $1,453, which is why its first-year return at our rates is about 43%. The machine produces exactly what it always did.
That is the pattern worth internalising. Buying a proven machine a year or two into its life, once its price has settled, is one of the few genuinely free improvements available in this business.
- 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.