Antminer S21 Hydro vs Bitdeer SealMiner A3 Hydro
Side-by-side specs, profitability, and home mining comparison.
Specifications Comparison
| Antminer S21 Hydro | Specification | Bitdeer SealMiner A3 Hydro |
|---|---|---|
| 335.0 TH/s | Hashrate | 500.0 TH/s |
| 5,360 W | Power Consumption | 6,750 W |
| 16.0 J/TH | Efficiency | 13.5 J/TH |
| 50 dB | Noise Level | 50 dB |
| 15.8 kg | Weight | 20.5 kg |
| 18,288 BTU/hr | BTU Output | 23,031 BTU/hr |
| 44/100 | Home Mining Score | 44/100 |
| — | Release Year | — |
| SHA-256 | Algorithm | SHA-256 |
| Bitmain | Manufacturer | Bitdeer |
Profitability Comparison
Antminer S21 Hydro
Bitdeer SealMiner A3 Hydro
Based on BTC price of $79,032 and current network difficulty as of May 15, 2026. Actual results vary.
Verdict
Based on our multi-factor analysis, the Bitdeer SealMiner A3 Hydro wins on 3 of 4 factors (efficiency, hashrate, price-performance). The standout gap is 49% more hashrate (335 vs 500 TH/s) in the Bitdeer SealMiner A3 Hydro's favour. That said, the Antminer S21 Hydro isn't beaten everywhere — it still wins power consumption. The right pick still depends on your power cost and noise tolerance — the breakdowns above make that call concrete.
Spec Deltas
Here is every spec where the Antminer S21 Hydro and Bitdeer SealMiner A3 Hydro actually differ, with the gap quantified:
- Bitdeer SealMiner A3 Hydro 49% more hashrate (335 vs 500 TH/s)
- Antminer S21 Hydro 21% better power draw (5,360 vs 6,750 W)
- Bitdeer SealMiner A3 Hydro 16% better efficiency (16.0 vs 13.5 J/TH)
- Antminer S21 Hydro 23% better weight (15.8 vs 20.5 kg)
- Bitdeer SealMiner A3 Hydro 26% more heat output (18,288 vs 23,031 BTU/hr)
Cost & ROI Over Time
Sticker price versus what the miner actually earns back: the table below projects cumulative net profit at a $0.10/kWh electricity rate.
| Antminer S21 Hydro | Metric | Bitdeer SealMiner A3 Hydro |
|---|---|---|
| $9,500 | Upfront cost (MSRP) | $6,650 |
| -$0.68 | Daily net profit | $1.98 |
| -$9,748 | Net after 1 year | -$5,926 |
| -$9,997 | Net after 2 years | -$5,201 |
| -$10,245 | Net after 3 years | -$4,477 |
| Does not pay back at current rates (negative daily profit) | Payback period | Takes ~9.2 years to pay back at current rates |
Projections assume continuous operation, a flat $0.10/kWh rate, and no hardware degradation, pool fees, or BTC price change. Real-world ROI varies.
Best For...
Best for Profitability
Bitdeer SealMiner A3 Hydro$2.66/day higher profit at current rates.
Best for Home Mining
TieBoth miners are equally suitable for home use.
Best for Efficiency
Bitdeer SealMiner A3 Hydro13.5 J/TH — lower electricity cost per terahash.
Frequently Asked Questions
Is the Antminer S21 Hydro or Bitdeer SealMiner A3 Hydro more profitable?
At the current BTC price and a $0.10/kWh electricity rate, the Bitdeer SealMiner A3 Hydro is more profitable at $1.98/day compared to $-0.68/day for the Antminer S21 Hydro. Profitability depends heavily on your electricity rate — use the selector above to calculate with your actual costs.
Which is quieter, the Antminer S21 Hydro or Bitdeer SealMiner A3 Hydro?
Both miners have similar noise levels. Check the specs table above for exact decibel readings.
Which is better for home mining, the Antminer S21 Hydro or Bitdeer SealMiner A3 Hydro?
Both miners score similarly on our Home Mining Score. Consider your specific constraints (noise tolerance, available power, heat needs) to decide.
How far apart are the Antminer S21 Hydro and Bitdeer SealMiner A3 Hydro on J/TH?
The Antminer S21 Hydro runs at 16.0 J/TH while the Bitdeer SealMiner A3 Hydro runs at 13.5 J/TH — a difference of 2.5 J/TH. Lower efficiency means less electricity per terahash of mining power, directly reducing operating costs. In relative terms that is 16% better efficiency (16.0 vs 13.5 J/TH).
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