Search
Previous
Ten Antminer power supply units arranged in two rows on a speckled shop floor.

Bitmain Antminer S21+ 216T – Efficient SHA-256 Bitcoin Miner

$4,200.00
Next

Bitmain Antminer S21 Pro 234T – Efficient SHA-256 ASIC Miner

$4,200.00
A bare Antminer hashboard lying flat on a wooden floor, rows of heatsink strips facing up, seen from directly above.
Awaiting product image

Bitmain Antminer S21+ 235T | High-Performance SHA-256 Miner

The Bitmain Antminer S21+ 235T delivers ~235 TH/s hashrate for Bitcoin and BCH mining with ~3.8 kW power draw and ~16.5 J/TH efficiency. Ideal for high-performance mining operations. Available now at ING Mining.

Key specifications

Hashrate
235 TH/s ±3%
Power draw
3,877 W ±5%
Efficiency
16.5 J/TH
Input voltage
220–277 V AC, single phase, 50–60 Hz, 20 A (Bitmain S21 platform specification). A 208 V circuit is below Bitmain’s rated minimum for this family, and 110–120 V is not an option at all
Condition
Brand New (October Batch, 2025)
Cooling
4 x high-speed fans
Full specification table

Buying from ING Mining

  • PriceQuoted, not listedWe price this on condition, quantity and freight to your address. Call or email for current price and availability.
  • FreightQuoted with the unitFreight to your address is confirmed with the price, before you pay — multi-unit and pallet orders included.
  • ConditionNewAs described on this listing.
  • GradingGraded before listingThis unit’s own grade is in the description above — where a listing states none, it says so. The six-step bench procedure behind a grade is published in full.
  • WarrantyStated per unit, not per storeAny term for this machine is in the description above. Ask for the return terms on this exact unit before you pay — full terms are in the Shipping & buying tab below.
Get a price+1 (781) 577-0377ns@ingmining.comwho we are

Sold by ING Mining LLC — ING MINING® is a registered U.S. trademark.

Price:

Live Chat
  • Condition graded per unit: new, tested working, refurbished or as-is
  • Warranty and returns stated per unit, not per store
  • Ships UPS Ground within 7 business days

Description

The Bitmain Antminer S21+ 235T is one of the most powerful SHA-256 ASIC miners available, built to deliver unmatched performance for Bitcoin (BTC) and Bitcoin Cash (BCH) mining. With an impressive 235 TH/s hashrate and an efficiency of 16.5 J/TH, it provides the ideal balance of high productivity and energy efficiency for modern mining operations.

Specifications

Condition Brand New (October Batch, 2025)
Manufacturer Bitmain
Model Antminer S21+ (235 TH/s)
Algorithm SHA-256
Hashrate 235 TH/s ±3%
Power consumption 3,877 W ±5%
Efficiency 16.5 J/TH
Input voltage 220–277 V AC, single phase, 50–60 Hz, 20 A (Bitmain S21 platform specification). A 208 V circuit is below Bitmain’s rated minimum for this family, and 110–120 V is not an option at all
Noise 75 dB
Cooling 4 x high-speed fans
Networking Ethernet connection
Operating temperature 5°C – 45°C
Warranty Bitmain publishes 365 days on BTC miners from the S19 generation onward, counted from its own shipment date and subject to the sales contract (Bitmain’s published warranty table, read 15 August 2026). This listing states no term of ours. What is left on a specific unit depends on when it shipped and is checkable by serial — ask and we will check it with you before you pay

What’s in the box

  • 1 × Antminer S21+
  • Nothing that is not listed above. Cords, controllers, brackets and spares are only included when this listing names them — if you need to know before you pay, ask on +1 (781) 577-0377 or ns@ingmining.com and we will confirm in writing what is physically in the crate

Performance & Efficiency

The S21+ 235T features advanced 5-nm chip technology that maximizes hash performance while maintaining lower energy draw. Thanks to its optimized thermal management system, it ensures stable, continuous 24/7 operation — ideal for both industrial-scale farms and individual miners.

Questions buyers ask about this machine

What will it cost to run?

That depends on your electricity rate, so here is the part we can state exactly: at 3,877 W running 24/7, this machine burns about 2,791 kWh a month. Multiply that by your own all-in rate per kWh — including delivery charges, not just the supply rate — to get your monthly power bill. We do not publish profitability figures, because they change with difficulty and price every day.

How loud is it?

75 dB — about as loud as a household vacuum cleaner running continuously, and it does not stop. This is a garage, workshop, outbuilding or hosted-facility machine, not something to put in a room where people live or sleep.

What can I mine with it?

The algorithm is SHA-256, and ASIC silicon is single-purpose: it will mine coins on that algorithm and nothing else, whatever the price of anything else does.

Is this a new unit?

Yes — new stock, as described in this listing. Any manufacturer warranty term that applies is stated in the description above; where none is stated, none is claimed.

Shipping cost for this exact item, and how warranty and returns work here, are answered in the Shipping & buying tab on this page. Anything else, ask a person on +1 (781) 577-0377 or ns@ingmining.com — we would rather talk before you buy.

Related hardware and where this sits in the store

Other air-cooled Antminer hardware at a similar duty:

Categories: Air Cooling, Bitmain Antminer, Bitcoin miner and New ASIC miners.

Where this sits: 235 TH/s at 16.5 J/TH makes this 11th of 24 by efficiency among the SHA-256 machines we stock, and the power alone runs $9.30 a day at $0.10/kWh. We list 2 machines at that same 16.5 J/TH, so between them the only thing that changes is how much work you get for the same power per unit. That is 50% more power per unit of work than the Bitmain Antminer S23 318T Mix at 11 J/TH, and whether the gap is worth the price difference is the whole decision. Every row is on the SHA-256 comparison table.




Where this listing sits

This one is on the new shelf. New stock, as described in the listing. Any manufacturer warranty term that applies is named in the description; where none is named, none is claimed.

What our grades mean

These are the only words we use, and each one means a specific thing. They are not interchangeable and we do not soften them to move stock.

NewUnused stock. Factory sealed unless the listing says otherwise — “new, open box” means exactly that, and the listing will say it.
Tested workingSecond-hand, and it ran on our bench at the hashrate the listing states. We measured it; we are not repeating what the last owner told us. Expect cosmetic wear.
RefurbishedTested working, plus work done: cleaned, thermal paste and fans dealt with, failed components replaced. The listing says what was actually done to that unit rather than using the word as decoration.
As-is / for partsSold with no working claim at all, at a price that reflects it. Buy these to repair or to harvest. If a listing says as-is, assume it does not hash until you have proved otherwise.
UntestedWe have it, we have not powered it, and we are not going to pretend we did. Rarer than as-is and always stated explicitly.

What a grade here does not mean

  • Cosmetic wear is not a fault. Dust, scratches, scuffed labels and discoloured plastics are normal on hardware that has been earning. We photograph what we have; if the pictures matter to you, ask for more and we will take them.
  • A grade is not a warranty. Warranty terms are stated per listing, never per store — see the Shipping & buying tab. A tested-working grade describes what the machine did on our bench, not what we owe you in six months.
  • A boosted hashrate is not a spec. Where a unit ships on tuned firmware we say so and we give the factory figures too, because overclocking raises power faster than it raises hashrate — a tuned machine is less efficient per terahash than stock, not more.
  • We will not invent a grade to fill a field. If a unit came in without history and has not been through the bench, its listing says that.

How the grade gets decided

A used-hardware seller who will not tell you how they test is asking you to take the grade on trust. Ours is published: the six-step bench procedure every machine goes through, and the five measurements that get recorded — per-board hashrate, chip count, measured wall power rather than the nameplate figure, hardware error rate, and temperature under sustained load. When it reaches you, run the 48-hour acceptance test straight away, while the freight claim window is still open.

Buying second-hand for the first time? How to buy a used ASIC miner without getting burned is the long version, written from the repair bench rather than from a spec sheet.

Shipping

This listing is quoted rather than priced, and freight is quoted with it. Tell us where it is going and we will confirm the shipping cost to that address with the price, before you pay — on a multi-unit or pallet order that is the only honest way to do it.

Outside the United States the checkout quotes a flat international rate. On multi-unit or pallet orders, contact us before ordering so freight to your destination can be confirmed properly. What to check when the pallet arrives, and how a freight claim works, is covered in the mining hardware shipping guide.

What to do the day it arrives

Photograph the pallet or the box before you open it, and keep the packaging until you are satisfied. Freight claim windows are short, and damage found on day two is a conversation while damage found on day thirty is an argument.

Then run the 48-hour acceptance test straight away, while that window is still open. It is the same ground our own bench covers, so you can compare like for like: how the grade on this listing was arrived at, and the five measurements we record, are set out in the Condition & grading tab on this page.

Condition, warranty and returns

Condition: New — as described on this listing.

Warranty is stated per listing, not across the catalogue. Some units carry a manufacturer term and say so above, naming the term and the date it runs from. Many units, particularly used and AS-IS stock, carry none, and those listings do not claim one. There is no blanket warranty covering a catalogue that runs from sealed factory stock to a hashboard sold for parts. For what a mining warranty normally covers, see ASIC miner warranty explained.

Returns: ask for the terms on this unit before you pay. No single returns window is published for the whole store, because the sensible terms on a tested working machine and on a board sold AS-IS for parts are not the same terms. Email or call and ask what applies to this exact item — it is a two-minute conversation and a great deal cheaper than a dispute.

Where you are going to run it

Two questions decide whether a machine like this works where you live, and neither of them is about the miner: can the circuit carry it, and what does your electricity cost? Most full-size machines here want a dedicated 240 V circuit and run at 70–75 dB continuously. A few do not — the Avalon Q publishes 45–65 dB and runs on 110–240 V — so read the voltage and noise figures on this listing rather than assuming. ASIC miner power requirements covers breaker sizing and what the install actually involves; cooling covers where the heat and the noise end up.

If your power is not genuinely cheap, hosting is the question to be asking instead of which miner to buy. Break-even electricity rate is hashprice divided by (24 × J/TH), and hashrate cancels out of it entirely — which is why a cheap old machine on expensive power loses money faster than an expensive new one does. The buying guide has the arithmetic; work out your own number before you buy anything.

If hosting is the answer, get written answers on three things before you sign: who pays for repairs, what the uptime commitment actually pays out when it is missed, and how curtailment is handled. A flat per-machine monthly rate is where most of the unpleasant surprises live. Types of mining farm compares the models and hosting versus cloud mining covers why owning the hardware is the better end of that trade. Ask us before you commit — it is a five-minute call and a great deal cheaper than a contract you cannot get out of.

What we do once it is racked, wherever that is. Deployment, firmware and monitoring are a service we run rather than a line on a page: pool and network setup, Braiins OS or VNish tuning, offline alerts, and board-level fault-finding when a machine stops hashing — ASIC mining consulting sets out what that covers. The hosting agreement itself is between you and the facility. What we can give you is the number most hosting disputes turn on: what this machine measured at the wall on our bench, so a shortfall on site is a figure to compare against rather than an argument about what it should have been doing.

Who you are buying from

ING Mining LLC, Hanson, Massachusetts. ING MINING® is a registered U.S. trademark; our marketplace feedback is on the reviews page and the longer version of who we are is on about. Reach a person on +1 (781) 577-0377 or ns@ingmining.com.

Our Related Products

Related products

Type to search