S21 or S23 – what the new generation brings and who should wait for it

Bitmain sells two generations side by side. The S21 series is in stock, the S23 series is available as a pre-order. The difference comes down almost entirely to one number: efficiency.

Efficiency compared

Hydro units from our shop:

• S21e Hyd: 17 J/TH
• S21+ Hyd: 15 J/TH
• S21e XP Hyd: 13 J/TH
• S23 Hyd: 9.5 J/TH
• S23 XP Hyd: 8.9 J/TH

From the S21+ Hyd to the S23 Hyd, power consumption per terahash falls by 37%.

More hashrate per unit

An S21+ Hyd delivers 358 or 395 TH/s, an S23 Hyd 563 TH/s (Bitmain states 580 TH/s in the manual), an S23 XP Hyd 600 TH/s. The power draw per unit stays in the same range of 5 to 6 kW. If you already have the rack spaces, connections and cooling capacity, the new generation gives you about half as much hashrate again from the same infrastructure.

What this means for the electricity price

The electricity price up to which a unit runs at a profit is inversely proportional to its efficiency. A unit with 9.5 J/TH can take an electricity price 58% higher than one with 15 J/TH before it has to switch off. So if the network's revenue falls, the new generation is still running when the old one has already stopped.

The case against waiting

• The price per terahash. The new generation costs considerably more per terahash. With very cheap electricity, the older unit earns back the capital invested faster.
• The waiting time. A pre-order earns nothing until delivery. A unit in stock is running a few days after payment.
• Hydro only. The S23 units in our shop are water-cooled. If you have no cooling circuit and do not want to build one, you stay with the S21 series, which is also available air-cooled.

Which generation for whom

S23, if your electricity is expensive, if your connection or your cooling sets the limit and you want to get as much hashrate out of it as possible, or if you are planning for many years.

S21, if your electricity is very cheap, if the infrastructure is already in place and every day without a unit costs money, or if you want to work with air cooling.

The calculation for your case

For both units, calculate the daily profit at your electricity price and divide the purchase price by it. Repeat this with a much lower revenue. If the same unit wins in both calculations, the decision is clear. If the result flips, it comes down to how much revenue risk you want to carry: the more efficient unit is the insurance against bad years.

Sources

• Bitmain, manuals (PDF): S23 Hyd, S21+ Hyd, S21e Hyd, S21e XP Hyd
• Bitmain Shop: Antminer S23 XP Hyd, specifications and delivery date

As of October 2026. Prices and delivery dates change; the calculation methods are not a promise of revenue.