Yes, the Antminer S21 series can still be worth mining in 2026, particularly for operators with low electricity rates, efficient cooling and existing mining infrastructure. However, profitability varies significantly between the original S21, S21 Pro, S21 XP and hydro-cooled models.
An original Antminer S21 may continue generating positive operating cash flow when electricity is inexpensive. Its margin becomes much smaller as the power rate approaches $0.08/kWh. More efficient models, including the S21 Pro and S21 XP, are generally better positioned to remain profitable if Bitcoin mining revenue falls or network difficulty rises.
Existing owners and new buyers must answer different financial questions. If you already own an S21, running it may make sense whenever pool revenue exceeds electricity, cooling, maintenance and other avoidable costs. If you plan to buy one in 2026, the miner must also recover its hardware price, shipping, electrical installation and supporting infrastructure.
Before evaluating a specific machine, miners should understand how Bitcoin mining works and why hashrate, network difficulty, power consumption and pool performance all influence profitability.
Antminer S21 Series Hashrate and Energy Efficiency
The Antminer S21 series includes several air-cooled and hydro-cooled SHA-256 miners. These machines can mine Bitcoin and other compatible SHA-256 cryptocurrencies, including Bitcoin Cash and Bitcoin SV.
Although the miners belong to the same product family, they do not have identical operating economics. Hashrate affects potential revenue, while power efficiency determines how much electricity is required to produce that hashrate.
Hashrate and Power Consumption of Different S21 Models
According to the official Antminer S21 specifications, the original model produces 200 TH/s while consuming 3,500 W. Its rated efficiency is 17.5 J/TH.
The S21 Pro increases hashrate to 234 TH/s with a rated wall-side power draw of 3,510 W. Its efficiency improves to 15 J/TH. This means it produces approximately 17% more hashrate than the original S21 while consuming almost the same amount of electricity.
The air-cooled S21 XP provides another substantial improvement. A representative version produces 270 TH/s at 3,645 W, resulting in an efficiency of 13.5 J/TH. Compared with the original S21, it delivers 35% more hashrate while using only about 4% more rated power.
| Model | Rated Hashrate | Rated Power | Efficiency | Cooling |
|---|---|---|---|---|
| Antminer S21 | 200 TH/s | 3,500 W | 17.5 J/TH | Air |
| Antminer S21 Pro | 234 TH/s | 3,510 W | 15 J/TH | Air |
| Antminer S21 XP | 270 TH/s | 3,645 W | 13.5 J/TH | Air |
| Antminer S21 Hyd. | 335 TH/s | 5,360 W | 16 J/TH | Hydro |
| Antminer S21 XP Hyd. | 473 TH/s | 5,676 W | 12 J/TH | Hydro |
These are typical manufacturer ratings rather than guaranteed operating results. Bitmain states that the actual hashrate of certain models may fluctuate by approximately 3%, while wall-side power consumption and efficiency may vary by approximately 5%.
Air-Cooled vs. Hydro-Cooled S21 Miners
Air-cooled S21 miners are generally easier to install because their integrated fans move air across the hashboards. They still require a suitable high-voltage circuit, a continuous supply of cool air and a direct route for hot-air exhaust.
Noise is a major limitation. The S21 Pro and S21 XP can reach approximately 76 dBA under maximum fan conditions. These are industrial machines and are normally unsuitable for bedrooms, offices or shared residential spaces.
Hydro-cooled miners provide greater hashrate density without relying on the high-speed cooling fans used by air-cooled models. The S21 XP Hyd., for example, delivers 473 TH/s at 12 J/TH.
However, hydro models require compatible pumps, piping, coolant, heat exchangers and monitoring systems. The S21 XP Hyd. also needs 380–415 V three-phase power. A mining farm with existing hydro infrastructure may deploy it efficiently, but constructing a new cooling system for one machine could eliminate its hardware-level advantage.
Miners deciding between these designs should first compare the practical requirements of air-cooled and hydro-cooled miners.
Pool-Side Hashrate, Uptime and Mining Stability
The hashrate displayed on the local miner dashboard does not always equal the hashrate credited by the mining pool. Pool-side performance depends on accepted shares, connection quality, miner stability and continuous uptime.
Operators should monitor:
- Average pool-side hashrate over at least 24 hours
- Accepted and rejected share rates
- Hashboard and chip temperatures
- Hardware errors
- Fan speed and airflow
- Pool disconnections
- Unexpected restarts
- Actual operating uptime
A miner running at 97% uptime produces approximately 3% less revenue than a calculation based on uninterrupted operation. That difference can eliminate a narrow profit margin, particularly for an original S21 operating near its electricity break-even point.
Antminer S21 Mining Revenue and Electricity Costs
Electricity is normally the largest recurring expense in Bitcoin mining. Even an efficient ASIC can become unprofitable when its electricity cost exceeds the value of its mining output.
The calculations below use an illustrative mining revenue rate of $0.0341 per TH/s per day. Mining revenue changes with Bitcoin price, network difficulty, transaction fees and total network hashrate. Miners should replace this assumption with current pool or hashprice data before making a purchasing decision.
Estimated Gross Mining Revenue
Daily gross revenue can be estimated by multiplying the miner’s hashrate by the current mining revenue per terahash.
At $0.0341 per TH/s per day, the representative S21 models would generate approximately:
- Antminer S21: $6.82 per day
- Antminer S21 Pro: $7.98 per day
- Antminer S21 XP: $9.21 per day
- Antminer S21 Hyd.: $11.42 per day
- Antminer S21 XP Hyd.: $16.13 per day
These figures represent gross revenue. They do not include electricity, pool fees, cooling, rejected shares, maintenance or downtime.
This distinction is important when evaluating whether Bitcoin mining is still profitable. A machine can generate Bitcoin every day while still losing money after its operating costs are deducted.
Daily and Monthly Electricity Consumption
The original S21 draws 3.5 kW at its rated performance. Running it continuously requires 84 kWh per day and approximately 2,520 kWh over a 30-day month.
At $0.05/kWh, its electricity cost would be $4.20 per day or $126 per month. At $0.08/kWh, the cost would increase to $6.72 per day or $201.60 per month.
The S21 XP consumes slightly more total power than the original S21, but it produces considerably more hashrate. This is why energy efficiency in J/TH is more useful than total wattage alone when comparing mining rigs.
Net Profit at Different Electricity Rates
The original S21’s operating result changes sharply as the power rate rises.
| Electricity Rate | Daily Electricity Cost | Daily Gross Revenue | Estimated Daily Net |
|---|---|---|---|
| $0.04/kWh | $3.36 | $6.82 | $3.46 |
| $0.05/kWh | $4.20 | $6.82 | $2.62 |
| $0.06/kWh | $5.04 | $6.82 | $1.78 |
| $0.08/kWh | $6.72 | $6.82 | $0.10 |
| $0.10/kWh | $8.40 | $6.82 | -$1.58 |
These results are calculated before pool fees, cooling, maintenance and downtime. At $0.04–$0.06/kWh, an existing S21 may still generate positive operating cash flow. At $0.08/kWh, almost all its theoretical revenue is consumed by electricity.
Break-Even Electricity Price
The theoretical break-even electricity rate equals daily gross revenue divided by daily electricity consumption.
For the original S21, $6.82 divided by 84 kWh produces a theoretical break-even electricity rate of approximately $0.081/kWh.
This does not mean an operator paying $0.081/kWh will earn a true net profit. Pool fees, rejected shares, cooling systems, repairs and downtime reduce the practical break-even rate.
A prudent operator should maintain a safety margin below the theoretical threshold. Under the assumptions used here, an all-in electricity rate below approximately $0.07/kWh would provide the original S21 with more protection against normal revenue fluctuations, although profitability would still not be guaranteed.
Antminer S21 Hardware Price and Payback Period
A mining rig can be worth operating without being worth buying. An existing owner mainly needs to determine whether future revenue exceeds avoidable operating costs. A new buyer must recover the machine price and every expense required to bring it online.
New and Used S21 Miner Prices
S21 prices vary by model, hashrate version, equipment condition, seller and market demand. Buyers should confirm the exact specifications instead of relying only on the model name.
Before buying a used S21, check:
- Rated model and hashrate version
- Pool-side performance during a sustained test
- Missing or unstable hashboards
- Chip and hardware error logs
- Fan and power supply condition
- Evidence of corrosion, dust or overheating
- Previous repair history
- Remaining warranty coverage
A low purchase price can shorten payback, but only if the machine remains reliable. An unstable miner may lose more through repairs and downtime than the original discount saves. Buyers comparing available hardware can also review JSBIT’s guide to the best Bitcoin miners.
Total Setup and Cooling Costs
The complete investment includes more than the miner price. An air-cooled S21 may require electrical upgrades, compatible power cables, PDUs, network equipment, ventilation and noise control.
A realistic budget should include:
- Mining hardware
- Shipping and import duties
- Electrical installation
- Breakers, cables and PDUs
- Ventilation or cooling equipment
- Network equipment
- Shelving and exhaust ducting
- Spare parts
- Maintenance reserves
Hydro-cooled models also require pumps, piping, coolant and heat-rejection equipment. These expenses must be included when comparing a hydro miner with an air-cooled alternative.
Payback Period Under Changing Bitcoin Prices and Difficulty
Static payback period = Total initial investment ÷ Estimated daily net profit.
Assume an original S21 has a total installed cost of $2,000 and earns an estimated $2.62 per day at $0.05/kWh. Its simple payback period would be approximately 763 days, or about 25 months.
That result assumes revenue and electricity costs never change, which is unrealistic. Increasing network difficulty can reduce the amount of Bitcoin earned per terahash, while a rising Bitcoin price may improve dollar-denominated revenue.
Before buying an S21, calculate at least three scenarios:
- A base case using current revenue and electricity costs.
- A bearish case with mining revenue 20% lower.
- A bullish case with mining revenue 20% higher.
The investment becomes risky if a modest decline in hashprice removes the operating profit or pushes the payback period beyond the machine’s expected useful life.
Which Antminer S21 Model Is Still Worth Mining?
The original S21 is most attractive to operators who already own the machine and have access to inexpensive electricity. It is more efficient than many older S19-generation miners, but its operating margin is weaker than that of later S21 models. Miners considering an upgrade can compare these economics with current Antminer S19 profitability.
The S21 Pro is a balanced option for air-cooled mining. It produces more hashrate than the original S21 while consuming almost the same rated power. Its 15 J/TH efficiency provides better protection against declining mining revenue.
The S21 XP is the strongest air-cooled model in this comparison. Its 270 TH/s hashrate and 13.5 J/TH efficiency provide substantially more output without a major increase in total power. However, it still requires industrial electrical service, strong airflow and effective noise management.
The S21 XP Hyd. offers the best efficiency and highest hashrate density among these models. It is better suited to established mining facilities with compatible three-phase power and hydro-cooling infrastructure.
When to Keep Running, Upgrade or Shut Down an S21
Continue running an S21 when its pool revenue consistently exceeds electricity, cooling, pool and maintenance costs by an acceptable margin.
Consider upgrading when the additional revenue and electricity savings from a more efficient machine can recover the price difference within a realistic operating period.
Consider shutting down or using a flexible operating schedule when:
- Electricity exceeds the practical break-even rate
- Cooling costs remove the remaining profit
- Hashboards require frequent repairs
- Pool-side hashrate remains below expectations
- Lower electricity rates are available only during certain hours
- Selling the hardware produces a better financial result
These decisions should use actual wall-side power and pool revenue rather than manufacturer ratings alone.
Conclusion: Is the Antminer S21 Series Still Worth It?
The Antminer S21 series is still worth mining in 2026 when electricity is inexpensive, cooling is efficient and the equipment maintains high uptime. An existing original S21 can remain profitable at low power rates, but its margin becomes extremely small as electricity approaches $0.08/kWh under the assumptions used in this article.
The S21 Pro and S21 XP offer better efficiency and greater protection against declining hashprice. The S21 XP Hyd. can deliver excellent performance in an industrial mining farm, but only when its cooling and three-phase power requirements are economically justified.
Existing owners should compare future mining revenue with avoidable operating costs. New buyers must evaluate the complete installed cost and test the investment against lower mining revenue, higher network difficulty and realistic downtime.
The S21 series is not obsolete, but it is no longer profitable under every condition. Electricity price, hardware cost, cooling overhead and actual pool-side performance ultimately determine whether a particular S21 is still worth mining.
Operators ready to compare purchase costs and deployment requirements can contact JSBIT for current Antminer pricing.
Antminer S21 Series FAQs
How Much Does an Antminer S21 Earn per Day?
An original 200 TH/s Antminer S21 earns approximately $6.82 per day in gross revenue at a mining revenue rate of $0.0341 per TH/s per day. Electricity, pool fees, cooling, maintenance and downtime must be deducted to calculate its actual net profit.
What Electricity Price Does an S21 Need to Be Profitable?
An original S21 needs an electricity rate below approximately $0.081/kWh under the revenue assumptions used in this article. Its practical break-even rate is lower after pool fees, cooling, rejected shares and other operating expenses are included.
Is the S21 Pro More Profitable Than the Original S21?
Yes, the S21 Pro is generally more profitable under the same electricity and mining-revenue conditions. It produces 234 TH/s at 3,510 W, compared with 200 TH/s at 3,500 W for the original S21, giving it higher gross revenue and better energy efficiency.
Should You Buy a Used Antminer S21?
Yes, a used Antminer S21 can be worth buying when its price, condition and conservative payback period are favorable. Test its pool-side hashrate, hashboards, fans, power supply, temperatures and error logs before purchasing.
