Antminer S21 vs Antminer S9
Side-by-side specs, profitability, and home mining comparison.
Specifications Comparison
| Antminer S21 | Specification | Antminer S9 |
|---|---|---|
| 200.0 TH/s | Hashrate | 14.0 TH/s |
| 3,500 W | Power Consumption | 1,350 W |
| 17.5 J/TH | Efficiency | 96.4 J/TH |
| 75 dB | Noise Level | 76 dB |
| 14.6 kg | Weight | 4.2 kg |
| 11,942 BTU/hr | BTU Output | 4,606 BTU/hr |
| 36/100 | Home Mining Score | 83/100 |
| — | Release Year | — |
| SHA-256 | Algorithm | SHA-256 |
| Bitmain | Manufacturer | Bitmain |
Profitability Comparison
Antminer S21
Antminer S9
Based on BTC price of $78,139 and current network difficulty as of May 16, 2026. Actual results vary.
Verdict
A dramatic cross-generation comparison spanning nearly a decade of mining hardware evolution. The S9 defined an era; the S21 defines the current one.
The S21 is roughly 5-6x more efficient than the S9, producing far more hashrate per watt. The S9 is no longer profitable as a pure miner at any realistic electricity rate but remains popular as a Bitcoin-powered space heater through D-Central's Space Heater editions.
Spec Deltas
The Antminer S21 and Antminer S9 diverge on the metrics below — each gap expressed as a real percentage, not a vague "better":
- Antminer S21 1329% more hashrate (200.0 vs 14.0 TH/s)
- Antminer S9 61% better power draw (3,500 vs 1,350 W)
- Antminer S21 82% better efficiency (17.5 vs 96.4 J/TH)
- Antminer S21 1% better noise (75.0 vs 76.0 dB)
- Antminer S9 71% better weight (14.6 vs 4.2 kg)
- Antminer S21 159% more heat output (11,942 vs 4,606 BTU/hr)
- Antminer S9 131% more home mining score (36.0 vs 83.0)
Cost & ROI Over Time
Hardware cost is only half the story — here is how each miner's upfront price plays out against cumulative profit at a $0.10/kWh rate.
| Antminer S21 | Metric | Antminer S9 |
|---|---|---|
| $5,500 | Upfront cost (MSRP) | — |
| -$1.21 | Daily net profit | -$2.74 |
| -$5,941 | Net after 1 year | -$999 |
| -$6,382 | Net after 2 years | -$1,998 |
| -$6,823 | Net after 3 years | -$2,997 |
| Does not pay back at current rates (negative daily profit) | Payback period | — |
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
TieBoth miners produce similar daily profit.
Best for Home Mining
Antminer S9Score: 83/100. 76 dB noise level.
Best for Efficiency
Antminer S2117.5 J/TH — lower electricity cost per terahash.
Frequently Asked Questions
Is there any reason to still use an Antminer S9?
Yes — as a space heater. The S9's 1400W power consumption generates significant heat output. D-Central's Space Heater S9 Edition converts this into usable home heating while still mining BTC as a bonus, effectively subsidizing your heating bill.
How much more efficient is the S21 than the S9?
The S9 runs at approximately 98 J/TH while the S21 achieves around 17.5 J/TH. That is roughly 5.6x more efficient, meaning the S21 produces 5.6 times more hashrate per watt of electricity consumed.