Guide · Nov 6, 2026 · 4 min read
What is a good J/TH for a bitcoin miner? The machines on sale run from 8.9 to 22
J/TH is the electricity a miner needs for each terahash of work, and lower is better. Today's machines on sale span 8.9 to 22. Where yours should sit depends on one number, the price you pay per kilowatt-hour, and the table below shows how.
TL;DR
- J/TH is the electricity a machine needs per terahash; lower is better.
- Machines on sale run from 8.9 to 22 J/TH, with 17.0 in the middle.
- The power price decides the J/TH you can afford: about 22 at 6¢, 13 at 10¢.
J/TH is the electricity a machine uses for each unit of work
Every bitcoin miner has two numbers on its label that matter most: how much work it does, in terahashes per second (TH/s), and how much power it draws, in watts. Divide the second by the first and you get joules per terahash, J/TH. It is the electricity a machine burns for each unit of work it does, so a lower number is a better machine.
A 17 J/TH machine and a 9 J/TH machine that both do 500 TH/s are not the same: the first draws about 8,500 watts and the second about 4,500. The spec sheet guide shows where each number sits on the label.
The machines on sale today run from 8.9 to 22 J/TH
On 6 November 2026 we list 140 industrial bitcoin machines in stock. The most efficient is 8.9 J/TH and the least efficient is 22.0. The middle one is 17.0. Two are under 10, 31 are between 10 and 15, 100 are between 15 and 20, and seven are 20 or above.
Cooling splits the range. The 12.0 to 21.5 J/TH range of the air-cooled machines has a middle of 15.5, while the water-cooled and immersion machines go lower, down to 8.9, and also include older models up to 22.0. A good number is always read against machines with the same cooling, because a hydro machine needs a water loop that an air-cooled site does not have. The cooling guide explains the difference.
Under 13 J/TH is excellent today. Between 13 and 18 is the middle of the market. Over 20 only works on cheap power.
What each J/TH costs to run for a day
To turn J/TH into dollars, multiply it by 0.024 and by the price of a kilowatt-hour. The result is the electricity for one terahash for one day. Scale it to a petahash, a thousand terahashes, and you can set it next to hashprice, what a petahash earns in a day, which was $32.22 on 6 November 2026 on our hashprice chart.
The table does that for four efficiencies at three power prices. Each cell is the electricity for one petahash for one day, with the share of that day's hashprice it uses in brackets. It leaves out the pool's fee and any time the machine is offline.
| Efficiency | Power at 3.9¢ | Power at 6¢ | Power at 10¢ |
|---|---|---|---|
| 9 J/TH | $8.42 (26%) | $12.96 (40%) | $21.60 (67%) |
| 13 J/TH | $12.17 (38%) | $18.72 (58%) | $31.20 (97%) |
| 17 J/TH | $15.91 (49%) | $24.48 (76%) | $40.80 (127%) |
| 21 J/TH | $19.66 (61%) | $30.24 (94%) | $50.40 (156%) |
The power price decides which J/TH you can afford
Read across the 21 J/TH row. At 3.9¢ it uses 61% of hashprice. At 6¢ it uses 94%, which leaves almost nothing. At 10¢ it uses 156% and loses money every day. The 9 J/TH machine at 10¢ uses 67% of hashprice, so it still works where the other cannot.
That gives a rule you can check yourself. The break-even efficiency is hashprice divided by 0.024 and by the power price, per terahash. At today's hashprice that is about 34 J/TH at 3.9¢, 22 at 6¢, 13 at 10¢ and 9 at 15¢. Nothing for sale is above 22, so every machine on the list clears its electricity at 6¢ today, the 22.0 one only just, and only the best ones do at 10¢.
Hashprice moves, so the line moves with it. The hashprice guide shows how, and the power price guide shows what a rate does to profit.
A worked example with one machine
Take a machine that does 200 TH/s at 17 J/TH. It draws 200 times 17, which is 3,400 watts. Over a day that is 3.4 kilowatts for 24 hours, or 81.6 kilowatt-hours.
At 6¢ a kilowatt-hour the electricity is $4.90 a day. At today's hashprice the machine's 200 terahashes earn about $6.44 a day, so about $1.55 is left, a quarter of the earnings. At 3.9¢ the electricity is $3.18 and about $3.26 is left, more than half. Same machine, same day; only the power price changed.
Pool fees and downtime come off the earnings, and the figures move every day with hashprice. The point of the example is the shape: electricity is the large cost, and J/TH is the lever on it. Halve the J/TH and you halve the daily electricity bill for the same work, which is why two machines that look alike on a shelf can be very different businesses once they are switched on.
Three ways to misread J/TH
The first is comparing across coins. A machine that mines another coin on a different algorithm quotes its efficiency in different units, such as joules per gigahash, and the numbers cannot be set against a bitcoin machine's. The guide on other coins explains why.
The second is taking the label as what you will see. J/TH on the label is the maker's figure at full power. A machine running in a lower power mode, or reporting a lower hashrate than its spec, will show a different number. Our guides on power modes and on why hashrate reads lower than the spec sheet cover both.
The third is chasing the lowest number whatever the power price. At 3.9¢ a machine at 17 J/TH leaves about half of hashprice after electricity, and a 9 J/TH machine buys a margin you may not need yet. At 10¢ the same choice decides whether you make money at all.
Three machines that mark the range
At the efficient end sits the Antminer S23 XP Hyd, water-cooled, at 600 TH/s and 5,340 watts: 8.9 J/TH. The best air-cooled machine on the list is the Whatsminer M74S+, at 332 TH/s and 3,984 watts: 12.0 J/TH.
At the other end is the Antminer S19 XP, air-cooled, at 141 TH/s and 3,010 watts: 21.35 J/TH. It does less than half the work of the M74S+ for three quarters of the power.
None of the three is the right one for everybody. The S23 needs a water loop, the M74S+ gives up some efficiency to run on air, and the S19 XP only works where power is cheap. The number tells you what a machine costs to run, and your power price tells you which of the three that cost suits.
A lower J/TH also keeps a machine earning through a halving
Efficiency does a second job. When the block reward halves, hashprice falls sharply with it, and the machines that stay above their electricity line are the efficient ones. The guide on halvings walks through it.
Efficiency decides what you spend every day; the purchase price decides what you spend once. The price of the box is not the whole price of getting a machine running, as the all-in price guide shows.
What it means for a miner
Start with the power price you will pay, work out the break-even from the rule above, and look only at machines comfortably under it. Then compare those on the price of the box. The checklist for a first machine covers the rest of what to look at before you buy.
At the cheapest end the arithmetic is kind. On the most efficient machine in stock, the 8.9 J/TH Antminer S23 XP Hyd, at 3.9¢ in Nigeria, the electricity for one bitcoin comes to about $19,500 against a market price of $75,506. That figure leaves out the machine and the pool fee, and output is never guaranteed.
Pick the J/TH from your power price, then compare machines inside that band.
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.