MB
Michal Beno
Chief Executive Officer, OneMiners · 2 September 2026
Every mining operator faces this question on a schedule: the new generation is more efficient, the old machines still work, and the difference between a good decision and an expensive one is a calculation most people never run. This article runs it. The answer is not the one the marketing suggests, and it depends entirely on whether you are replacing working hardware or buying new capacity.
THE SHORT ANSWER
Should you upgrade from the Antminer S21 XP to the S23?
Not by replacing working machines — but yes for new capacity. The S23 Hydro is 21% more efficient (9.5 vs 12.0 J/TH) and survives a far deeper downturn, covering its power bill down to a hashprice of $10.94 per PH/s per day against $13.82 for the S21 XP Hydro. But at today's hashprice of $37.85 the cheaper S21 XP Hydro still returns more profit per dollar invested, paying back in 17.9 months against 25.9 months. The S23 only becomes the better capital allocation once hashprice falls below about $120.00 per PH/s per day.
ON THIS PAGE
Two different questions
"Should I upgrade?" hides two questions that have opposite answers, and conflating them is how fleets get replaced too early.
1Should I replace a working S21 XP with an S23? Here the old machine's purchase price is already spent. It is a sunk cost and it must be ignored. The only comparison that matters is the S23's full price against the difference in operating profit — a very high bar that current-generation hardware rarely clears while the old unit still runs profitably.
2Should my next purchase be an S23 or an S21 XP? Here both prices are live and the comparison is fair. This is the question this article answers with real numbers.
The mistake that costs the most money
Replacing hardware that is still covering its electricity bill and generating profit. A working machine on cheap fixed power is producing free cash; scrapping it to buy efficiency you do not yet need converts that cash flow into a capital expense. Efficiency matters when the market turns against you — not before.
Generation to generation
| Machine | Hashrate | Power | Efficiency | Price | Net/day |
|---|---|---|---|---|---|
 Antminer S21 XP 270 TH/s |
270 TH/s | 3,645 W | 13.50 J/TH | $3,159 | $6.02 |
 Antminer S21 XP Hyd 473 TH/s |
473 TH/s | 5,676 W | 12.00 J/TH | $6,199 | $11.37 |
 Antminer S23 (Air) 318 TH/s |
318 TH/s | 3,498 W | 11.00 J/TH | $6,899 | $8.01 |
 Antminer S23 Hydro 580 TH/s |
580 TH/s | 5,510 W | 9.50 J/TH | $12,299 | $15.61 |
The S21 and S23 generations, air and hydro variants, at $0.0480/kWh. Efficiency improves down the table; price does not improve with it.
₿ MINES BITCOIN (BTC)
Antminer S23 Hydro 580 TH/s
580 TH/s5,510 W9.50 J/THHydro
The current generation: 9.5 J/TH and the deepest downturn tolerance in the pair.
$12,299
View on OneMiners →
₿ MINES BITCOIN (BTC)
Antminer S21 XP Hyd 473 TH/s
473 TH/s5,676 W12.00 J/THHydro
The previous generation at a fraction of the price — and still the capital-efficiency leader at today's hashprice.
$6,199
View on OneMiners →
Break-even hashprice: the survival number
Break-even hashprice is the single most useful number in mining and almost nobody quotes it. It is the market price of hashrate at which a machine's revenue exactly equals its electricity cost. Above it you profit. Below it you are paying to run a heater.
Today hashprice is $37.85 per PH/s per day. Here is how far each machine can fall at $0.0480/kWh before it stops paying for its own power.
| Machine | Efficiency | Break-even hashprice | Margin below today |
|---|---|---|---|
| Antminer S23 Hydro 580 TH/s |
9.50 J/TH | $10.94/PH/day | -71% |
 Antminer S23e Hyd 2U 865 TH/s |
10.00 J/TH | $11.52/PH/day | -70% |
| Antminer S23 (Air) 318 TH/s |
11.00 J/TH | $12.67/PH/day | -67% |
| Antminer S21 XP Hyd 473 TH/s |
12.00 J/TH | $13.82/PH/day | -63% |
| Antminer S21 XP 270 TH/s |
13.50 J/TH | $15.55/PH/day | -59% |
 Antminer S21 Pro 245 TH/s |
15.00 J/TH | $17.28/PH/day | -54% |
 Antminer S21 188 TH/s |
17.50 J/TH | $20.16/PH/day | -47% |
Lower break-even hashprice means a longer survival runway. Calculated at $0.0480/kWh; on more expensive power every figure rises proportionally.
This is what efficiency actually protects you from
The S23 Hydro keeps covering its power bill until hashprice falls 71% from here. An older S21 at 17.5 J/TH runs out of room after only 47%. Research from CoinShares has put 15–20% of the global fleet below water in weak markets, and that fleet is made almost entirely of high-J/TH machines on expensive power. Efficiency is insurance, and insurance only pays out when things go wrong.
Profit per dollar invested
Efficiency is the survival metric. Return on capital is the buying metric, and on that measure the older machine currently wins — because it is dramatically cheaper.
| Machine | Price | Net/day | Net per $1,000 invested | Payback |
|---|---|---|---|---|
| Antminer S21 188 TH/s |
$1,111 | $3.33 | $3.00 | 11.0 months |
| Antminer S21 Pro 245 TH/s |
$2,059 | $5.04 | $2.45 | 13.4 months |
| Antminer S21 XP 270 TH/s |
$3,159 | $6.02 | $1.91 | 17.2 months |
| Antminer S21 XP Hyd 473 TH/s |
$6,199 | $11.37 | $1.83 | 17.9 months |
| Antminer S23 (Air) 318 TH/s |
$6,899 | $8.01 | $1.16 | 28.3 months |
| Antminer S23 Hydro 580 TH/s |
$12,299 | $15.61 | $1.27 | 25.9 months |
| Antminer S23e Hyd 2U 865 TH/s |
$19,440 | $22.78 | $1.17 | 28.0 months |
 Antminer S23 Hyd 3U 1.16 PH/s |
$28,399 | $31.22 | $1.10 | 29.9 months |
Net profit per $1,000 of purchase price per day, at $0.0480/kWh. This is the honest measure of what your capital earns, and it ranks almost exactly opposite to the efficiency table above.
Read those two charts together and the whole upgrade question becomes clear. The newest machines are the most efficient and the worst value per dollar. The older machines are the best value per dollar and the first to fail in a downturn. You are not choosing better or worse hardware — you are choosing which risk you would rather carry.
Where the crossover actually is
Because efficiency and capital efficiency pull in opposite directions, there is a hashprice at which they cross. Below that point the S23 Hydro's lower operating cost outweighs its higher purchase price, and it becomes the better capital allocation. Solving for it gives $120.00 per PH/s per day.
| Hashprice scenario | S21 XP Hyd net per $1k/day | S23 Hydro net per $1k/day | Winner |
|---|---|---|---|
| $60.00/PH/day | $3.52 | $2.31 | Antminer S21 XP Hyd |
| $45.00/PH/day | $2.38 | $1.61 | Antminer S21 XP Hyd |
| $37.85/PH/day (today) | $1.83 | $1.27 | Antminer S21 XP Hyd |
| $25.00/PH/day | $0.85 | $0.66 | Antminer S21 XP Hyd |
| $18.00/PH/day | $0.32 | $0.33 | Antminer S23 Hydro |
| $14.00/PH/day | $0.01 | $0.14 | Antminer S23 Hydro |
| $11.00/PH/day | $-0.22 | $0.00 | Antminer S23 Hydro |
Net profit per $1,000 of capital per day at $0.0480/kWh, across hashprice scenarios. The crossover sits at roughly $120.00 per PH/s per day. Hashrate forwards have recently priced six months out below spot, so a falling hashprice is not a hypothetical scenario.
What this means in plain terms
At today's $37.85 hashprice, buying the cheaper S21 XP Hydro returns capital faster. If you expect hashprice to fall under about $120.00 and stay there — which a sustained difficulty climb would deliver — the S23 Hydro is the better allocation, and it also keeps running long after the S21 stops. The choice is really a view on the next two years of difficulty.
Should you replace, or add?
For anyone running an existing fleet, this is the decision that matters. The test is straightforward:
1Is the old machine still profitable at your rate? An S21 XP Hydro nets about $11.37 per day at $0.0480/kWh. If that number is positive, the machine is producing cash and there is no operational reason to remove it.
2Is it constraining something scarce? If your facility allocation is full, the old machine is occupying a megawatt that a more efficient machine could use more productively. That is a real reason to replace — capacity, not efficiency.
3Would the resale value plus the efficiency gain cover the new machine? The S23 Hydro's advantage over the S21 XP Hydro is $4.24 per day, or $1,548 a year. Against a $12,299 purchase, that alone takes 95.3 months to recover.
4If the answer to all three is no, add rather than replace. New capacity in the new generation, old capacity left to run until it stops paying for itself.
| Machine | Units per MW | Hashrate per MW | Net per day | Net per year |
|---|---|---|---|---|
| Antminer S21 XP Hyd 473 TH/s |
176 | 83.3 PH/s | $2,003 | $730,914 |
| Antminer S23 Hydro 580 TH/s |
181 | 105.3 PH/s | $2,833 | $1,033,912 |
One megawatt of connected load, filled entirely with each machine. This is the comparison that matters once contracted capacity rather than capital is your limiting factor.
The megawatt view is where the new generation wins unambiguously. The same one megawatt of contracted capacity yields 26.3% more hashrate filled with S23 Hydros than with S21 XP Hydros. When capacity is your constraint rather than capital — which is the normal condition for hosted operators — efficiency converts directly into revenue.
The verdict
YOU ALREADY RUN S21 XP MACHINES
Keep them running, add S23
They still net about $11.37 a day at $0.0480/kWh. Let them earn; put new capital into the new generation instead of replacing cash flow with a capital expense.
YOU ARE BUYING YOUR FIRST MINERS
Antminer S21 XP Hyd
Best capital efficiency in the range at $1.83 per $1,000 invested per day, and 17.9 months to payback at current hashprice.
YOU ARE FILLING CONTRACTED MEGAWATTS
Antminer S23 Hydro
More hashrate per megawatt and the lowest break-even hashprice of the pair at $10.94. When capacity is scarce, efficiency is revenue.
How every number on this page was produced
Bitcoin figures use a hashprice of $37.85 per PH/s per day, derived from a BTC price of $76,768 and a network hashrate of 912.6 EH/s (difficulty 125.81T) on 2 September 2026. That is block subsidy only — transaction fees are excluded, so the revenue side is deliberately conservative. Zcash uses 1,440 ZEC per day to miners (80% of emission after the development fund) against a 24.48 GSol/s network. Scrypt credits both chains a merged-mining unit actually earns, Litecoin and Dogecoin. Electricity is charged at the OneMiners network average of $0.0480/kWh unless a table states otherwise, with no performance or management fee, because OneMiners charges none. Payback assumes difficulty and price hold still, which they never do — treat it as a ranking tool, not a forecast.
Run the upgrade math on your own fleet
The crossover hashprice on this page depends on the exact prices you can buy at today and the rate you actually pay. Both change. Compare the current generation against the previous one at live pricing before every purchase.
Open the mining calculators →
Frequently asked questions
Is the Antminer S23 better than the S21 XP?
On efficiency, clearly: 9.5 J/TH against 12.0 J/TH for the hydro variants, a 21% improvement. On return per dollar invested at today's hashprice, no — the S21 XP Hydro earns $1.83 per $1,000 per day against $1.27 for the S23 Hydro. Both statements are true at once.
Should I sell my S21 XP to buy an S23?
Generally not while the S21 XP is still profitable. Its purchase price is sunk, so the only gain is the daily difference of $4.24, which takes 95.3 months to repay a full S23 Hydro purchase before counting resale proceeds. Replace when capacity is the constraint, or when the old machine stops covering its power.
What is break-even hashprice and why does it matter?
It is the market price of hashrate at which a machine's revenue exactly covers its electricity cost. Today's hashprice is $37.85 per PH/s per day. The S23 Hydro breaks even at $10.94 and the S21 XP Hydro at $13.82 at $0.0480/kWh. The lower number is a longer runway through a downturn, and it is the best single predictor of which machines are still running in three years.
How much more hashrate does a megawatt of S23 Hydros produce?
About 26% more than the same megawatt of S21 XP Hydros — 105.3 PH/s against 83.3 PH/s. That is the efficiency gain expressed the way a hosted operator experiences it.
At what point does the S23 become the better buy?
When hashprice falls below roughly $120.00 per PH/s per day. Above that the cheaper S21 XP Hydro returns capital faster; below it the S23's lower operating cost dominates. Since hashrate forwards have priced six months out below spot, that scenario deserves serious weight rather than being dismissed.
Do older machines still make sense in 2026?
On genuinely cheap fixed power, yes. An Antminer S21 at 17.5 J/TH still nets about $3.33 a day at $0.0480/kWh and pays back in 11.0 months because it costs so little. The same machine on home power at $0.1200/kWh loses $2.36 a day. The hardware did not change — the electricity rate decided the outcome.
Does the S23 come in an air-cooled version for upgrades?
Yes. The S23 Air delivers 318 TH/s at 11.00 J/TH, which is better efficiency than the S21 XP Hydro despite needing no coolant loop. For an air-cooled site that wants current-generation efficiency without re-plumbing, it is the natural upgrade path.
How often should a mining fleet be refreshed?
Let the numbers decide rather than the calendar. A machine earns its place as long as its revenue exceeds its electricity cost and it is not occupying capacity a better machine could use. In practice, with fixed low-cost power and a long warranty, current-generation hydro hardware stays economically useful for many years — which is why fixed 7-year fixed electricity and a 7-year warranty change the refresh calculus so significantly.
Data sources
- Bitcoin network hashrate and difficulty: mempool.space mining API, 2 September 2026.
- BTC, ZEC, LTC, DOGE, KAS and ALEO spot prices: CoinGecko, 2 September 2026.
- Zcash, Litecoin and Dogecoin network hashrate: Blockchair chain statistics, 2 September 2026, cross-checked against difficulty.
- Kaspa network hashrate and block reward: Kaspa public API, 2 September 2026.
- Hardware specifications, pricing and product photography: the OneMiners live catalogue.
- Manufacturer specifications: Bitmain and IceRiver product documentation.
- Efficiency-tier revenue spreads and hashprice history: Hashrate Index research.
- Share of the global fleet running at a loss: CoinShares mining research.
DISCLAIMER
This article is published for informational and educational purposes only and is not financial, investment or tax advice. Every profitability figure is a scenario built on the market data stated above, captured on 2 September 2026. Cryptocurrency prices, network difficulty, mining rewards and hardware pricing all change constantly, and a change in any one of them changes every result on this page. Mining returns are not guaranteed and no fixed profit guarantee applies. Hardware specifications reflect the OneMiners catalogue and manufacturer documentation at the time of writing. Always run your own numbers against current market conditions and your own electricity rate before purchasing mining hardware.
