The Bitmain Antminer S21 series represents a major leap forward in ASIC mining technology, delivering powerful performance and improved energy efficiency for SHA-256-based cryptocurrencies. As one of the most advanced mining rigs available, the S21 lineup offers multiple configurations tailored to different operational scales—from individual miners to large data centers. With enhanced chip architecture, superior cooling options, and high hash rates, these devices are engineered for maximum uptime and profitability.
Whether you're upgrading from an older model like the Antminer S19 or entering the mining space for the first time, this guide covers everything you need to know about the S21 series: specifications, supported coins, setup instructions, profitability estimates, and firmware updates—all optimized for seamless integration with modern mining pools.
Key Models in the Antminer S21 Lineup
The Antminer S21 family includes several variants, each designed with specific use cases in mind. Below is a breakdown of the core models:
Antminer S21 (Standard)
- Hashrate: 200 TH/s
- Power Consumption: ~3,550W
- Cooling: Air-cooled
- Overview: Ideal for entry-level mining operations, this model improves upon previous generations with better thermal management and reliability.
Antminer S21 Pro
- Hashrate: 234 TH/s
- Power Consumption: ~3,550W
- Cooling: Air-cooled
- Overview: Offers higher efficiency than the base model while maintaining similar power draw—making it one of the most popular choices among miners.
Antminer S21 Hydro
- Hashrate: 335 TH/s
- Power Consumption: ~5,360W
- Cooling: Water-cooled
- Overview: Features liquid cooling for reduced noise and improved temperature control, perfect for indoor or densely packed setups.
Antminer S21 Immersion
- Hashrate: 301 TH/s
- Power Consumption: ~5,570W
- Cooling: Full immersion (submerged in dielectric fluid)
- Overview: Maximizes hardware longevity and thermal stability, suitable for industrial-scale deployments.
Antminer S21 Hydro 3U
- Hashrate: 860 TH/s
- Power Consumption: ~11,180W
- Cooling: Water-cooled
- Overview: Designed for server rack installations, this high-density unit delivers exceptional throughput for enterprise-level mining farms.
The S21 Pro stands out as the most balanced option, combining strong hashrate with efficient power usage—ideal for cost-conscious miners seeking long-term returns.
Supported Cryptocurrencies and Merged Mining
All models in the S21 series support SHA-256 algorithm coins, including:
- Bitcoin (BTC)
- Fractal Bitcoin (FB)
- eCash (XEC)
- DigiByte (DGB)
- Bitcoin Cash (BCH)
One of the standout features available through compatible mining pools is merged mining, which allows simultaneous mining of BTC and FB without splitting hash power. This means you can earn rewards from both networks using the same computational effort—effectively boosting your revenue potential.
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Performance Metrics and Physical Specifications
Understanding size, weight, and power requirements helps in planning deployment logistics and infrastructure needs.
| Model | Hashrate | Power Use | Dimensions (cm) | Weight |
|---|---|---|---|---|
| S21 | 200 TH/s (±10%) | 3,550W (±10%) | 40 x 29 x 20 | 15.4 kg |
| S21 Pro | 234 TH/s (±10%) | 3,550W (±10%) | 48 x 29 x 22 | 20 kg |
| S21 Immersion | 301 TH/s (±10%) | 5,570W (±10%) | 37 x 30 x 24 | 16.8 kg |
| S21 Hydro | 335 TH/s (±10%) | 5,360W (±10%) | 40 x 21 x 17 | 12.3 kg |
| S21 Hydro 3U | 860 TH/s (±10%) | 11,180W (±10%) | 90 x 49 x 14 | 20 kg |
These dimensions reflect compact designs even at high performance levels, enabling flexible installation options across home rigs and commercial facilities.
Hashrate Comparison Across Models
The Antminer S21 hashrate ranges significantly across variants—from 200 TH/s on the base model to a staggering 860 TH/s on the Hydro 3U edition. This scalability makes the series versatile:
- For hobbyists: The standard or Pro models offer excellent entry points.
- For professionals: The Hydro and Immersion versions provide industrial-grade output.
- For large-scale operators: The 3U rack-mountable unit delivers unmatched density and efficiency.
Higher hashrate directly correlates with increased block-solving probability and daily earnings—assuming stable network difficulty and electricity costs.
Mining Profitability Estimates
Current profitability (excluding electricity costs) varies by model:
| Model | Daily Earnings (Approx.) |
|---|---|
| S21 | $11.40 |
| S21 Pro | $13.30 |
| S21 Immersion | $17.10 |
| S21 Hydro | $19.10 |
| S21 Hydro 3U | $48.90 |
Note: Actual profits depend on real-time coin prices, network difficulty, and local energy rates.
To calculate your personalized return on investment, consider using a mining calculator that factors in your electricity rate and pool fees. Regular monitoring ensures you adapt quickly to market fluctuations.
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Step-by-Step Setup Guide
Getting your Antminer S21 online is straightforward when following these steps:
1. Prepare Hardware
- Connect the miner to a reliable power source using an appropriate PSU.
- Link it to your router via Ethernet cable for stable connectivity.
2. Power On
- Turn on the device. Fan activation indicates successful boot-up.
3. Locate IP Address
- Download the Bitmain IP Reporter Tool from Bitmain’s official site.
- Run the tool and press the "IP Report" button on the miner to detect its local network address.
4. Access Web Interface
- Open a browser and enter the detected IP address.
- Log in using default credentials:
root/root.
5. Configure Mining Pool
Navigate to “Miner Setting” and input your chosen pool’s details:
| Coin | Pool Address | Miner Name Format | Password |
|---|---|---|---|
| BTC + FB | stratum+tcp://btc.kryptex.network:7014 | WALLET_ADDRESS.WORKER_NAME | x |
| FB | stratum+tcp://fb.kryptex.network:7013 | WALLET_ADDRESS.WORKER_NAME | x |
| XEC | stratum+tcp://xec.kryptex.network:7036 | WALLET_ADDRESS.WORKER_NAME | x |
Replace WALLET_ADDRESS with your actual wallet and assign a worker name (e.g., AntminerS21) for tracking.
Ensure all three pool lines use consistent settings before saving.
6. Restart and Verify
After saving, the miner will reboot. Wait a few minutes, then log back in to check dashboard metrics: hashrate, temperature, uptime, and accepted shares.
Firmware Updates
Keeping your Antminer updated ensures optimal performance and security.
How to Update Firmware:
- Visit Bitmain’s official support page.
- Select BTC SHA256 algorithm and choose your model (e.g., Antminer S21 Pro).
- Download the latest firmware file.
- In the web interface, go to “Firmware Upgrade.”
- Upload the file and check “Keep settings” if you want to preserve configurations.
- Click “Upgrade” and wait—do not interrupt power during update.
Regular updates often include efficiency improvements and bug fixes that enhance long-term reliability.
Frequently Asked Questions
Q: Can I mine Bitcoin and Fractal Bitcoin at the same time?
Yes! Through merged mining on compatible pools, you can mine both BTC and FB simultaneously without any loss in performance or hash power allocation.
Q: What is the best cooling method for indoor mining?
Water-cooled models like the S21 Hydro offer quieter operation and better heat dissipation compared to air-cooled units—ideal for residential environments.
Q: How do I calculate my actual daily profit?
Use a mining calculator that includes your electricity cost per kWh, pool fee percentage, and current coin value to get accurate net profit estimates.
Q: Is immersion cooling worth it?
For large-scale operations where hardware lifespan and thermal management are critical, immersion cooling provides superior protection and reduced maintenance costs over time.
Q: Do all S21 models use the same firmware?
No—always download firmware specific to your exact model to avoid compatibility issues or bricking the device.
Q: How often should I update my miner’s firmware?
Only update when necessary—such as when new features or critical fixes are released. Avoid unnecessary updates unless they offer clear benefits.
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Final Thoughts
The Bitmain Antminer S21 series sets a new benchmark in ASIC mining with its blend of performance, efficiency, and flexibility. Whether you're running a single unit or managing a full-scale farm, selecting the right model—and configuring it properly—can significantly impact your bottom line. With support for merged mining, multiple cooling options, and scalable hashrate capabilities, the S21 line remains a top choice for serious cryptocurrency miners in 2025 and beyond.