The Antminer S21 Pro is one of the most efficient air-cooled Bitcoin miners on the market. At roughly 234 TH/s and 15 J/TH, it sits in the sweet spot between the standard S21 and the premium S21 XP. Here’s what that means for your returns.
The specs at a glance
| Algorithm | SHA-256 (Bitcoin) |
|---|---|
| Hashrate | ~234 TH/s (also sold in 220 & 245 TH/s tiers) |
| Power draw | ~3,510 W |
| Efficiency | ~15 J/TH |
| Cooling | Air-cooled, dual/quad fan (~75 dB) |
| Manufacturer | Bitmain |
All three hashrate tiers share the same 15 J/TH nameplate efficiency — the difference is binning, not a different chip. For the underlying concepts, see our ASIC miners explained guide.
Efficiency in context
15 J/TH is a meaningful step up from the standard S21 (17.5 J/TH) and a generational leap over S19-era machines. As network difficulty keeps climbing and the post-halving block reward stays at 3.125 BTC, that efficiency is what keeps the machine earning when older units stop.
Strengths
- Excellent 15 J/TH efficiency
- High hashrate density
- Strong resale value
Watch-outs
- ~3.5 kW needs proper power
- ~75 dB — not for living spaces
- Returns hinge on electricity cost
Host it or run it at home?
At 3,510 W running 24/7, the S21 Pro’s profitability is dominated by your electricity rate. On expensive residential power it can struggle; in a facility on cheap renewable energy it performs far better. We break the decision down fully in self-mining vs. hosting. For most owners, our mining hosting is the simplest route to a low, stable rate.
Verdict
If you want a current-generation Bitcoin miner that stays competitive as difficulty rises, the S21 Pro is one of the smartest buys in 2026 — provided you pair it with cheap power. You can buy it new or second-hand in our miners marketplace, or skip hardware with cloud mining.
Frequently asked questions
What hashrate does the Antminer S21 Pro have?
The most common configuration is 234 TH/s, with 220 TH/s and 245 TH/s tiers also sold. All share a 15 J/TH efficiency rating.
How much power does the S21 Pro use?
Around 3,510 W at the 234 TH/s tier, drawing roughly 3.3–3.7 kW across the tier range. Plan your circuit and PDU accordingly.
Is the S21 Pro good for home mining?
Only with a dedicated 220V+ circuit, real ventilation and tolerance for ~75 dB noise. Most owners get better economics and quiet by hosting it.
