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Machine review · Oct 6, 2026 · 4 min read

Whatsminer M70S review: the same coin cost as an S21 XP, at a higher price per terahash

MicroBT's 13.5 J/TH air-cooled machine makes a bitcoin for the same electricity as the S21 XP and clears its power at our Argentina site with room to spare. What separates the two is the price paid per terahash, and today that favours the Bitmain.

A MicroBT Whatsminer M70S air-cooled miner on a dark Firsthand card with the words Whatsminer M70S review, 13.5 J/TH, 258 TH/s air-cooled

MicroBT Whatsminer M70S (258 TH/s)

The bottom line

The M70S is MicroBT's mid-tier air-cooled Whatsminer: 258 TH/s from 3,483 W in the bin we list, 13.5 J/TH. At our Argentina site, at 6¢, it makes a bitcoin for about $42,800 of electricity and returns roughly 37% in its first year at today's price. That coin cost is the same as the S21 XP's, about $42,800, because the two machines share an efficiency.

Bought once its price settled, in July 2026, it has mined and kept 0.0123 BTC for $509 of power: $554 of cashflow against a $5,101 landed cost, which is what the first months of a four-year machine look like. Between now and the 2028 halving it has another 0.068 BTC in it, worth about $8,481 with bitcoin back at its previous high, roughly 1.8× its hardware by the halving, with the machine still running afterwards.

What you are buying is current-generation efficiency in a box you can put on a shelf. What you are paying for it is $12.60 a terahash, against $11.55 for the S21 XP, which is why the S21 XP's year-one return of 39% beats this machine's 37%. The efficiency is equal; the entry price is not.

Scores

CriterionScoreWhy
Cashflow6/10Makes a bitcoin for about $42,800 of electricity at 6¢ and returns roughly 37% in year one. It has covered 11% of its hardware so far and is on track for about 1.8× by the 2028 halving. Held back by the price per terahash: the S21 XP returns about 39%.
Longevity7.5/10At 13.5 J/TH its line is $19.44 a petahash a day at 6¢, just under half of the 5 October hashprice of $41.17 ($20.59). That is the same position as the S21 XP, with more room at Nigeria's 3.9¢, where the line is $12.64.
Efficiency8/1013.5 J/TH is the efficiency of the best air-cooled machines we sell. MicroBT's own 12.5 J/TH tier, the M70S+, sits one step above it.
Quality control5/10Scored as unknown rather than as good. The series is under a year old and we found no operator reports of its boards in the field that we could cite, so there is no record to score.
Serviceability6/10MicroBT lists a one-year warranty with repair services within its scope. Hosted with us in Argentina, a repair is billed at the cost of parts only.

Weighted on what an owner gets back per dollar over the next four years. Efficiency puts it among the best air machines we stock; the price per terahash and an unproven failure record hold the score below the S21 XP.

Buy it if

Walk away if

What MicroBT shipped

MicroBT introduced the M70 series on 8 December 2025 at the Bitcoin MENA conference in Abu Dhabi, in three efficiency tiers: 14.5, 13.5 and 12.5 J/TH. The M70S is the middle one, air-cooled, listed at 226 to 258 TH/s at 13.5 J/TH.

MicroBT's own shop page shows the 248 TH/s bin at 13.5 J/TH and 3,348 W, in a chassis 430 mm long, 155 mm tall and 226 mm wide that weighs 13.5 kg. It takes a single 220 to 240 V supply through a C19 inlet and is rated for ambient air from -5 °C to 35 °C. The spec we use for the 258 TH/s unit, 3,483 W, is our store record, because the maker's page does not list that bin.

Above it in the same family sits the M70S+, MicroBT's 12.5 J/TH air tier. Below it, the plain M70 runs at 14.5 J/TH.

Chart: Coins kept since the first settled price we hold for it, the electricity that made them, and where it lands by the 2028 halving.

Priced like a new machine

The first price we hold for the 258 TH/s unit, on 24 April 2026, was $3,414. It is $3,251 today, $12.60 a terahash, for the same 258 TH/s at the same 13.5 J/TH. That is a settled price for a machine that has been on sale for under a year, and the best entry price we have on record for it.

Set against its peers, the price is the whole story. The S21 XP has the same 13.5 J/TH and costs $11.55 a terahash. The M7DS, also 13.5 J/TH and air-cooled, costs $10.92. The S21 Pro, a generation behind at 15 J/TH, costs $7.67. A machine's price per terahash settles to where its efficiency, its maker and its age put it, and the M70S has not finished settling. The guide to what a miner costs all-in shows what sits on top of the box.

The same efficiency as an S21 XP, at $12.60 a terahash against $11.55.

Chart: What the 258 TH/s unit has cost, from the first price we hold for it in April 2026.

What a coin costs it

At 6¢ in Argentina it makes a bitcoin for about $42,800 of electricity today, against a bitcoin price of $86,055. The S21 XP makes one for about $42,800 and the M7DS for about $42,800: all three share 13.5 J/TH, so electricity per coin is the same to within rounding. The S21 Pro, at 15 J/TH, needs about $47,600 and the A2 Pro Air about $47,300.

The return per dollar is where they part. In its first year the M70S returns about 37%, the S21 XP 39%, the M7DS 45% and the S21 Pro 46%. A lower price per terahash buys more hashrate for the money, and in the first year that outweighs a dearer coin. Efficiency pays later, once the halving arrives, which is what the next section is about.

Over its run since July 2026, electricity has averaged about $41,400 a coin. That is a short lifetime average; the figure to plan on is today's.

Chart: What a coin costs it in electricity against bitcoin's price. The gap between the lines is the cashflow.

Where the halving puts it

A machine's line is the hashprice at which it stops covering its own power. At 13.5 J/TH a petahash uses 324 kWh a day: $19.44 at 6¢, and $12.64 at Nigeria's 3.9¢. Network hashprice was $41.17 per petahash per day on 5 October on our hashprice chart, so the M70S clears the line at 6¢ by more than double.

The 2028 halving halves the coins a petahash earns. At today's price and difficulty that puts hashprice near $20.59, a little above the 6¢ line and well above the Nigerian one. That is today's conditions held flat, not a forecast: it is why every projection we publish assumes the old high returns, and the forward figures here do the same.

A 15 J/TH machine has a line of $21.60 at 6¢, which is above that halved level. That is the case for paying for 13.5 J/TH: it is the efficiency that survives the halving at the same site. The guide to efficiency and halvings shows where the line sits for every J/TH figure.

Chart: Network hashprice per petahash per day. The M70S needs about $19 of it at 6¢; half of today's level is just above that. Open the chart

What owning one is like

We looked for operator threads and repair write-ups on the M70S and found nothing specific to it that we could stand behind, so there are none quoted here. The series has been on sale for under a year, and a reliability score needs a record that this one has not had time to build.

What a fault costs is the part that matters. MicroBT lists a one-year warranty with repair services within its scope. Hosted with us in Argentina, a repair is billed at the cost of the parts and nothing else, and it is a line item, not a catastrophe. It is a 13.5 kg air-cooled unit that fits a standard shelf, which keeps handling simple.

We found no operator reports of this machine's boards we could cite. We score that as unknown, not as good.

Chart: Scored on what costs an owner money over a four-year life. Reliability is scored as unknown.

Our two cents

The M70S is a good machine at a price that has not settled yet. At 6¢ it clears its power with room today, it stays above its line after the halving, and a buyer who wants MicroBT hardware in an air-cooled rack has a sound reason to pick it.

Most buyers chasing the best return on the money should look at the S21 XP first: the same coin cost for $11.55 a terahash and a year-one return of about 39%. The figure below ranks what beats it on cost per coin and then on year-one return, in stock today. A coin that costs less to make is a coin you keep more of.

What beats it on cost per coin and on first-year return, in stock today.

Sources and further reading

Which machines this covers

Disclosure

Firsthand Bitcoin sells and hosts mining hardware, including this machine. No manufacturer, distributor or affiliate programme paid for or reviewed this page and we take no commission on the links above. Historical figures are computed from daily bitcoin price and network hashprice, each day valued at its own prices. Nothing here is investment advice.