Nobody wanted the T21. It quietly out-earned its own price.

Bitmain’s unglamorous budget line, bought at $2,765 and overlooked by most buyers. Two and a half years later it has produced $3,888 of cashflow and is on track for roughly 1.6× its hardware by the halving.

Bitmain Antminer T21 (190 TH/s)

The machine in the shadow of the S21

The T-series is Bitmain’s value line: the same generation of silicon, binned and configured for a lower price and a worse efficiency figure. The T21 shipped at 190 TH/s and 19 J/TH alongside an S21 doing 200 TH/s at 17.5, and most buyers looked at the two numbers and bought the S21.

Understandable, and on efficiency they were right. But the T21 cost less, and the thing about a cheaper box is that it needs to produce less to be worth having.

What 911 days produced

Bought at $2,765, landed at $4,533 in Argentina, and run at 6¢ since March 2024. It has mined and kept 0.082 BTC, worth about $6,667 today, for $2,779 of electricity — roughly $33,900 a coin.

That is $3,888 of cashflow, about 86% of its landed cost, with another 0.039 BTC and roughly $3,340 in it before the 2028 halving. On those figures it finishes near 1.6× its hardware and keeps going. It spent 144 days in Argentina and moved to Nigeria on 15 August 2024.

It is not a spectacular machine and this is not a spectacular result. It is a box that was bought cheap, ran without drama for two and a half years, and paid for itself with room to spare — which is all most people actually need from a miner.

It mined 0.082 BTC for $2,779 of electricity, on a machine that cost $2,765.

Chart: Coins kept, the electricity that made them, and where it lands by the 2028 halving.

The case for the unglamorous machine

At today’s rates the T21 still returns about 40% in its first year at our Argentina site. Its problem is not that it does not work — it is that 19 J/TH gives it a shorter runway than the machines around it, so its remaining life depends more than most on getting it onto cheap power.

Which is exactly what our Nigeria site is for. At 3.9¢ a 19 J/TH machine has years left; at 10¢ it would already be finished. The T21’s story is a good argument that the question is rarely "is this machine good" and almost always "is this machine good where I am putting it".

Bitmain Antminer S21 XP (270 TH/s) — 13.5 J/TH, In stock, $42,484 of electricity per bitcoin, 38% year one
Bitdeer SealMiner A2 Pro Air (256 TH/s) — 14.9 J/TH, In stock, $46,885 of electricity per bitcoin, 33% year one
Bitmain Antminer S21 Pro (234 TH/s) — 15 J/TH, In stock, $47,205 of electricity per bitcoin, 46% year one

What makes cheaper bitcoin if you are buying today rather than in 2024.

Which machines this covers

Bitmain Antminer T21 (190 TH/s)

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.