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Bitmain Antminer S21 XP vs MicroBT Whatsminer M66S+

Comparing
two miners
Decided by
Efficiency (J/TH, lower is better)
Last reviewed
2026-08-18
Bitmain Antminer S21 XP4.4

Bitmain's most efficient air-cooled miner: 270 TH/s at 13.5 J/TH, about 10 percent less power per terahash than the next tier of fan-cooled rigs.

MicroBT Whatsminer M66S+3.5

A water-cooled workhorse for the farm hedging against Bitmain: 318 TH/s at 16.5 J/TH on universal 100-240V input, with no three-phase upgrade required.

Verdict: Bitmain Antminer S21 XP

Bitmain Antminer S21 XP is the more efficient machine: 13.5 J/TH against 16.5 J/TH for MicroBT Whatsminer M66S+, on the rated watts and nominal hashrate each maker publishes.

Criterion
Efficiency (J/TH, lower is better)
Bitmain Antminer S21 XP
13.5 J/TH
MicroBT Whatsminer M66S+
16.5 J/TH

Bitmain Antminer S21 XP and MicroBT Whatsminer M66S+, fact by fact

Every row is from the two reviews as of their review dates, with sources on each. A check marks the side a decidable criterion favours; rows without one are information, not a score.

Bitmain Antminer S21 XP and MicroBT Whatsminer M66S+ compared fact by fact from their reviews; a check marks the side a decidable criterion favours.
FactBitmain Antminer S21 XPMicroBT Whatsminer M66S+
Efficiency13.5 J/TH (favoured on this row)16.5 J/TH
Editorial rating4.43.5
Hashrate270 TH/s318 TH/s
Power draw3,645 W5,247 W
Street price$3,800 to $5,500$8,000 to $10,500
Price per TH/s (midpoint)$17.22 (favoured on this row)$29.09
CoolingAirHydro (liquid loop)
Noise75 dBLow, water loop only
ReleasedOctober 20242025
Made byBitmainMicroBT
Best forHome and small operations that want flagship efficiency without running a water loopFarms that want a hydro Bitmain alternative on standard 100-240V power
Last reviewed2026-08-182026-08-18

Frequently asked questions

Is Bitmain Antminer S21 XP or MicroBT Whatsminer M66S+ more efficient?

Bitmain Antminer S21 XP is the more efficient machine: 13.5 J/TH against 16.5 J/TH for MicroBT Whatsminer M66S+, on the rated watts and nominal hashrate each maker publishes. Efficiency is derived from the record's rated watts and nominal hashrate and never stored, so it cannot disagree with the numbers beside it.

Which is better value, Bitmain Antminer S21 XP or MicroBT Whatsminer M66S+?

Bitmain Antminer S21 XP, at $17.22 per TH/s against $29.09, on the midpoint of each street-price band (Bitmain Antminer S21 XP $3,800 to $5,500, MicroBT Whatsminer M66S+ $8,000 to $10,500) as of the review dates. A cheaper terahash that burns more power costs more over a year at most electricity prices.

Which is quieter, Bitmain Antminer S21 XP or MicroBT Whatsminer M66S+?

Bitmain Antminer S21 XP: 75 dB, air cooling. MicroBT Whatsminer M66S+: Low, water loop only, hydro (liquid loop) cooling. Neither belongs in a room people use; the mining hub covers where each can actually run.

Which is newer, Bitmain Antminer S21 XP or MicroBT Whatsminer M66S+?

MicroBT Whatsminer M66S+, released 2025, against October 2024 for Bitmain Antminer S21 XP.

The full reviews: Bitmain Antminer S21 XP and MicroBT Whatsminer M66S+, each with its sources, and every miner we review.

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