Bitmain Antminer S21 vs MicroBT Whatsminer M66S

Mining profitability comparison for Bitcoin (BTC), Bitcoin Cash (BCH)

★ MicroBT Whatsminer M66S is more efficient for Bitcoin mining

Verdict: Bitmain Antminer S21 vs MicroBT Whatsminer M66S

For Bitcoin mining, the MicroBT Whatsminer M66S is the more efficient choice, delivering roughly 52% more hashrate per watt than the Bitmain Antminer S21. The MicroBT Whatsminer M66S draws 59W less, cutting electricity costs by about $36/year at $0.07/kWh. Bottom line: if power efficiency is your priority, the MicroBT Whatsminer M66S is the stronger pick — but confirm with your real electricity rate and current hardware prices below, since acquisition cost ultimately drives ROI.

Specifications

Spec Bitmain Antminer S21 MicroBT Whatsminer M66S
Type ASIC ASIC
Algorithm
Hashrate (BTC) 200 TH/s 298 TH/s
Power Draw 3500 W 3441 W
Efficiency 17.5 J/TH 11.5 J/TH
Supported Coins BTC, BCH BTC, BCH
Release Year N/A N/A

Hashrate & Efficiency per Coin

Coin Bitmain S21 HR MicroBT M66S HR Power A Power B More Efficient
BTC 200 TH/s 298 TH/s 3500 W 3441 W Whatsminer ✓
BCH 200 TH/s 298 TH/s 3500 W 3441 W Whatsminer ✓

Daily Electricity Cost at Different Rates

Electricity cost only (not including coin revenue). Lower is better for any given rate.

Electricity Rate Bitmain Antminer S21 MicroBT Whatsminer M66S Difference
$0.04/kWh $3.36 $3.30 +$0.06 (B cheaper)
$0.06/kWh $5.04 $4.96 +$0.08 (B cheaper)
$0.07/kWh $5.88 $5.78 +$0.10 (B cheaper)
$0.1/kWh $8.40 $8.26 +$0.14 (B cheaper)
$0.12/kWh $10.08 $9.91 +$0.17 (B cheaper)
$0.15/kWh $12.60 $12.39 +$0.21 (B cheaper)
$0.2/kWh $16.80 $16.52 +$0.28 (B cheaper)

Pros & Cons

Bitmain Antminer S21

  • 200 TH/s — strong absolute hashrate for Bitcoin mining
  • Lower acquisition cost than the S21 Pro (~$3,000–3,500)
  • Same chassis and power infrastructure as S21 Pro
  • Less efficient than S21 Pro (17.5 vs 15 J/TH)
  • 3,500 W power draw still requires industrial setup
  • Noise level identical to Pro (75 dB)

MicroBT Whatsminer M66S

  • Best efficiency of any MicroBT air-cooled ASIC (11.5 J/TH)
  • 298 TH/s — highest raw hashrate in MicroBT's air-cooled lineup
  • Proven MicroBT reliability at scale; immersion variant available (M66S+)
  • High acquisition cost (~$5,000–$6,500)
  • 3,441 W draw requires dedicated high-amperage circuit
  • MicroBT firmware ecosystem smaller than Bitmain's

Frequently Asked Questions

Is the Bitmain Antminer S21 or MicroBT Whatsminer M66S more profitable for Bitcoin mining?

Based on hashrate-per-watt efficiency, the MicroBT Whatsminer M66S is more efficient for Bitcoin mining. However, actual profitability depends on your electricity cost, hardware acquisition price, and coin price — use the live calculator for exact numbers.

What is the power consumption difference between the Bitmain Antminer S21 and MicroBT Whatsminer M66S?

For Bitcoin mining, the Bitmain Antminer S21 draws 3500 W while the MicroBT Whatsminer M66S draws 3441 W. The MicroBT Whatsminer M66S uses 59 W less power, which at $0.07/kWh saves ~$36 per year in electricity.

Can both the Bitmain Antminer S21 and MicroBT Whatsminer M66S mine the same coins?

Yes — both units can mine Bitcoin (BTC) and Bitcoin Cash (BCH). You can switch between these coins with a simple pool configuration change.

Which unit has a better ROI?

ROI depends on hardware acquisition price, electricity cost, and coin price trajectory. The more efficient unit (better J/TH or hashrate per watt) will generally have a lower operating cost per coin mined, but the absolute ROI timeline is determined by the purchase price. Always model both units in the MiningReturns calculator with your specific electricity rate and current market prices.

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Calculate real profitability

Enter your electricity rate for live earnings estimates on both units.

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