BITMAIN ANTMINER S21 PRO Review

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Overview

The Bitmain Antminer S21 Pro, released in March 2024, is one of BITMAIN’s flagship SHA‑256 ASIC miner optimized for Bitcoin, Bitcoin Cash, and Bitcoin SV, and Fractal Bitcoin. It delivers a blistering hashrate of 234 TH/s with a power consumption of 3510 W, achieving an impressive efficiency of 15 J/TH—among the best in its class.

About the Coin: Bitcoin & SHA‑256 Coins

Bitcoin (BTC) is the world’s first and largest Proof‑of‑Work blockchain, secured by ASIC miners running the SHA‑256 algorithm. The same hardware also supports mining Bitcoin Cash (BCH) and Bitcoin SV (BSV), and Fractal Bitcoin (FB) making the S21 Pro a versatile workhorse for these networks.

Exterior Design

The miner is housed in a sturdy metal case measuring 450 × 219 × 293 mm (without packaging) and weighing around 20 kg net, 22 kg gross  It sports Bitmain’s signature air‑cooled form factor, built for easy rack mounting and heat dissipation.

Packing

Antminer S21 was nearly identical in size to most S19 series miners. The S21 Pro however is much larger. Notice the package size difference in the between the two.

Size

While previous antminers used 120mm fans, S21 pro has 4x 140mm fans that makes it taller & wider. The hashboards are much longer as well. At 44 lbs net weight, the S21 pro is about 30% heavier than S21. Overall S21 pro is much larger than its predecessors.

Power Supply & PSU Details

    • Model: APW171215A V1.32
    • Input Voltage: 220–277 AC
    • Connectors: P14 Plug type 20AMP Power Ports comes with it’s AntWire
    • Efficiency: Engineered for stable voltage under ASIC-grade loads

Cooling System

Equipped with 4 high‑speed fans, configured for front‑to‑back airflow, the S21 Pro maintains optimal thermal conditions. Noise levels are around 76 dB at 25 °C operating temperature 

Fan Specifications

    • Model & Size: 4x Martech High-Pressure Fans, 140 × 140 x 38 mm
    • Count: 4 fans—front intake and rear exhaust (dual pair)
    • Voltage & Current: 12 V DC; 5 AMP
    • Speed & Airflow: ~5000k RPM, designed for max airflow
    • Noise Level: ~75–80 dB under full load

Internal Components

The S21 Pro houses 3 hashboards look similar to S21 and S19XP. They are aluminum backed with integrated bolt on heatsinks. Same pastel blue thermal compound that’s common on S21/T21 miners.

Control Board

S21 Pro using Amlogic A113D and Bitmain made substantial changes to the control board dimensions on S21 Pro, to match the wider body. Control board cover is now secured with two screws and is a bit easier to slide on/off. No LCD display on the control board/faceplate.

Hashboards & Hashing Performance

      • Hashrate: 234 TH/s ± 3%
      • Model: A3HB70601
      • Efficiency: ~15 J/TH ± 5%
      • Power Draw: ~3510 W
      • Hashboard Layout: 3x high-density boards, optimized for SHA-256

ASIC Chips

Antminer S21 Pro hashboard has only 65 chips on each hashboard, Model: BM1370BC. At stock setting each S21 Pro chip hashes at a whopping 1.2T! That is double the single chip hashrate of S21 chips!

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Operational Specs

    • Algorithm: SHA‑256 (BTC/BCH/BSV/FB) 

    • Voltage: 220–277 V AC

    • Operating Temp: –20 °C to 45 °C

    • Storage: –20 °C to 70 °C

    • Humidity: 10–90% non-condensing

    • Altitude: ≤ 2000 m (with derating above 900 m) 

    • Network: RJ45 Ethernet (10/100 Mbps)

Profitability Estimate (as of June 28, 2025)

Based on MiningNow

    • Hashrate: 234 TH/s

    • Power: 3.51 kW → 84.24 kWh/day

    • Electricity Cost @ $0.01/kWh: ~$15.33/day 

    • Profit Estimate Range: ~$15–$16/day depending on electricity rate and pool fees.

Conclusion

The Antminer S21 Pro is one of the most powerful and efficient SHA‑256 miners in 2025, with a 234 TH/s hashrate at just 15 J/TH. Its robust build, integrated PSU, and industrial cooling make it a top-tier choice for serious Bitcoin miners. Depending on electricity costs and BTC price, it can generate around $7–16 net profit per day, making it a strong candidate for both industrial and well-managed home mining operations.

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