Antminer S21 Series Explained: Pro, XP, Plus, e, Hyd and Immersion Models
Short answer: the Antminer S21 is Bitmain’s SHA-256 Bitcoin miner family, and the letters after “S21” tell you how a model is cooled and where it sits on efficiency. The air-cooled S21, S21+, S21 Pro and S21 XP run on 220-277 V single-phase power. Hyd (hydro) and Immersion models need a liquid-cooling setup and 380-415 V three-phase power. By Bitmain’s ratings, efficiency runs from 17.5 J/TH for the original S21 to 11 J/TH for the S21 XP+ Hyd.
This guide explains each suffix and lists Bitmain’s ratings for every S21 model we could verify. It is built from manufacturer specification sheets, not hands-on testing. Bitminers does not guarantee mining profitability.
On this page
- What the Antminer S21 family is
- What each S21 suffix means
- Antminer S21 models compared: Bitmain's ratings
- Air, hydro or immersion: what each type needs
- Antminer S21 Pro
- Bitmain Antminer S21 XP and S21 XP Hyd
- Antminer S21 Hydro models: S21 Hyd, S21+ Hyd and S21e Hyd
- How to narrow down an S21 model
- Frequently asked questions
What the Antminer S21 family is
Bitmain announced the S21 in October 2023 and has added variants since. Every model uses the SHA-256 algorithm and mines Bitcoin (BTC), Bitcoin Cash (BCH) and Bitcoin SV (BSV).
The figure that separates the variants most clearly is efficiency in joules per terahash (J/TH): power in watts divided by hashrate in TH/s. The base S21 draws 3,500 W for 200 TH/s, which is 17.5 J/TH. Lower means less energy for each terahash of work. Our guide to hashrate, terahash and J/TH covers the units in more detail.
What each S21 suffix means
Bitmain does not publish a glossary for its model suffixes, so the descriptions below are based on what its own specification tables show for each model.
- No suffix (S21): the original air-cooled model, rated at 17.5 J/TH.
- Pro: an air-cooled step up in efficiency to 15 J/TH. Bitmain’s shop lists three S21 Pro hashrate ratings: 220, 234 and 245 TH/s.
- + (Plus): the air-cooled S21+ is rated at 16.5 J/TH, between the S21 and the S21 Pro. The S21+ Hyd is a separate hydro model at 15 J/TH, so do not mix up the two.
- XP: the most efficient S21 tier for each cooling type: 13.5 J/TH air-cooled, 12 J/TH hydro and 13.5 J/TH in immersion (normal mode). The XP+ Hyd goes further, to 11 J/TH.
- e: used only on hydro models (S21e Hyd, S21e XP Hyd and the 3U rack unit). Each “e” model is rated slightly less efficient than the same model without the “e”: 17 versus 16 J/TH for the S21e Hyd against the S21 Hyd, and 13 versus 12 J/TH for the S21e XP Hyd against the S21 XP Hyd. Bitmain’s shop lists no air-cooled S21e, so this guide does not cover one.
- Hyd: hydro cooling. A liquid coolant loop carries heat away from the hashboards. Bitmain’s tables for hydro models specify inlet coolant temperature (20-50 °C on the newer units), flow rate and coolant type: antifreeze, pure water or deionized water.
- Immersion (Imm.): built to run submerged in dielectric oil. Bitmain rates its S21 immersion units in two working modes, NEM (normal) and HEM (high), with an oil flow of 1 m³/h.
- 3U: a rack-mount chassis three rack units tall. Bitmain sells the S21e XP Hyd 3U as “U3S21EXPH”. It measures 900 × 482.6 × 130 mm (482.6 mm is the standard 19-inch rack width) and weighs 42.7 kg.
Antminer S21 models compared: Bitmain’s ratings
The table lists Bitmain’s own ratings. Where Bitmain publishes more than one hashrate rating for a model, all are shown. Bitmain gives these as typical values: actual hashrate can vary by about ±3% and power by about ±5%. Air-cooled ratings are at 25 °C ambient, and hydro ratings are at 35 °C inlet coolant.
| Model | Cooling | Hashrate (TH/s) | Power (W) | J/TH | Input voltage |
|---|---|---|---|---|---|
| S21 | Air | 200 | 3,500 | 17.5 | 220-277 V single-phase |
| S21+ | Air | 216 | 3,564 | 16.5 | 220-277 V single-phase |
| S21 Pro | Air | 220 / 234 / 245 | 3,300 / 3,510 / 3,675 | 15 | 220-277 V single-phase |
| S21 XP | Air | 270 | 3,645 | 13.5 | 220-277 V single-phase |
| S21 Hyd | Hydro | 319 / 335 | 5,104 / 5,360 | 16 | 380-415 V three-phase |
| S21+ Hyd | Hydro | 358 | 5,370 | 15 | 380-415 V three-phase |
| S21e Hyd | Hydro | 288 / 310 | 4,896 / 5,270 | 17 | 380-415 V three-phase |
| S21 XP Hyd | Hydro | 473 | 5,676 | 12 | 380-415 V three-phase |
| S21e XP Hyd | Hydro | 430 | 5,590 | 13 | 380-415 V three-phase |
| S21 XP+ Hyd | Hydro | 480 | 5,280 | 11 | 380-415 V three-phase |
| S21e XP Hyd 3U (U3S21EXPH) | Hydro, 3U rack | 860 | 11,180 | 13 | 380-415 V three-phase |
| S21 Immersion | Immersion | 215 / 239 (NEM); 301 (HEM) | 3,440 / 3,824; 5,569 | 16 (NEM); 18.5 (HEM) | 380-415 V three-phase |
| S21 XP Immersion | Immersion | 300 (NEM); 380 (HEM) | 4,050; 5,700 | 13.5 (NEM); 15 (HEM) | 380-415 V three-phase |
The S21e Hyd 310 TH/s rating comes from Bitmain’s hosting-version listing; its standard listing shows 288 TH/s. Immersion units trade efficiency for extra hashrate in high mode.
Air, hydro or immersion: what each type needs
Air-cooled S21 models
The S21, S21+, S21 Pro and S21 XP use fans and plug into 220-277 V single-phase power. Bitmain lists 76 dBA for these models, so they need a dedicated space with strong airflow, not a living area.
Hydro (Hyd) models
Hyd units need a coolant loop with a pump and a dry cooler or heat exchanger, plus a 380-415 V three-phase supply. That voltage is not something a typical home outlet provides, so have an electrician confirm your site before ordering. Our guide to air cooling vs hydro cooling explains the infrastructure, and the hydro miners category lists every water-cooled model we carry.
Immersion models
Immersion units sit in a tank of dielectric fluid circulated through a heat exchanger, and also need three-phase power. See immersion cooling for Bitcoin mining and the immersion miners category. At the time of writing (October 4, 2026), the Antminer S21 XP Immersion 300 TH/s is $2,150.00 and the S21 Immersion 239 TH/s is $3,252.63.
Antminer S21 Pro
The Antminer S21 Pro is the middle step of the air-cooled line. All three of Bitmain’s ratings (220, 234 and 245 TH/s at 3,300, 3,510 and 3,675 W) work out to 15 J/TH, so the bins differ in hashrate and power draw but not in efficiency. Bitmain lists the unit at 450 × 219 × 293 mm and 18.5 kg. Its S21 Pro specification page gives the 234 TH/s rating.
At the time of writing (October 4, 2026), Bitminers lists the Antminer S21 Pro 234 TH/s at $2,379.00. The 220 TH/s listing is also $2,379.00 and the 245 TH/s listing is $2,869.43.
Bitmain Antminer S21 XP and S21 XP Hyd
The Bitmain Antminer S21 XP is the most efficient air-cooled S21: 270 TH/s at 3,645 W, or 13.5 J/TH, measuring 449 × 219 × 293 mm and 18.7 kg. The S21 XP Hyd moves the XP design to hydro cooling. It is rated at 473 TH/s and 5,676 W (12 J/TH) on 380-415 V three-phase power at 12 A, and it measures 339 × 173 × 207 mm and weighs 13.8 kg.
At the time of writing (October 4, 2026), the Antminer S21 XP 270 TH/s is $3,799.00 and the Antminer S21 XP Hyd 473 TH/s is $6,669.00. We also list the S21 XP+ Hyd at 500 TH/s for $9,124.50. Bitmain’s own current S21 XP+ Hyd batch is rated at 480 TH/s and 5,280 W.
Antminer S21 Hydro models: S21 Hyd, S21+ Hyd and S21e Hyd
“Antminer S21 hydro” usually means the S21 Hyd, but three hydro models share that base. The S21 Hyd is rated at 16 J/TH, the S21+ Hyd at 15 J/TH and the S21e Hyd at 17 J/TH. All three take 380-415 V three-phase power. According to Bitmain’s support specification, the S21 Hyd measures 339 × 163 × 207 mm and weighs 12.3 kg.
At the time of writing (October 4, 2026), the Antminer S21 Hyd 335 TH/s is $4,200.00 and the S21e Hyd 310 TH/s is $1,679.00.
How to narrow down an S21 model
- Start with your power supply. Single-phase 220-277 V limits you to the air-cooled models. A three-phase 380-415 V supply opens up hydro and immersion.
- Match the cooling you can run. Do not buy a Hyd or Immersion unit without the loop or tank it depends on.
- Compare J/TH, not only TH/s. A higher-hashrate unit with a worse J/TH rating uses more energy for each terahash.
- Check the form factor. The 3U unit is built for racks and draws 11,180 W per machine.
Every S21 we carry is in the Antminer S21 category. For Bitmain’s newer generation, which is rated as low as 8.9 J/TH, see the Antminer S23 category.
Frequently asked questions
What is the difference between the Antminer S21 Pro and the S21 XP?
Both are air-cooled and use 220-277 V single-phase power. Bitmain rates the S21 Pro at 15 J/TH (220-245 TH/s) and the S21 XP at 13.5 J/TH (270 TH/s), so the XP uses less energy per terahash.
What does “Hyd” mean on an Antminer S21?
Hyd means hydro cooling: a liquid coolant loop instead of fans. Hyd models need a pump and heat-rejection equipment, plus 380-415 V three-phase power.
Can I run an Antminer S21 Hyd at home?
Only if your site can provide 380-415 V three-phase power and a coolant loop. Most homes cannot without major electrical and plumbing work, so check with an electrician first.
Is there an air-cooled Antminer S21e?
We found none. Bitmain’s shop uses the “e” only on hydro models: the S21e Hyd, the S21e XP Hyd and the 3U rack unit (U3S21EXPH).
How accurate are Bitmain’s hashrate ratings?
Bitmain gives them as typical values: actual hashrate can vary by about ±3% and power by about ±5%. Results also depend on ambient or coolant temperature.