Bitcoin’s projected difficulty cut would still leave older S19 rigs short at 5-cent power

Bitcoin miners could earn about 7% more per unit of computing power if a projected difficulty cut materializes, but the relief would leave two older S19 variants needing electricity near 4 cents per kilowatt-hour just to cover machine power.

Hashrate Index’s November 9 snapshot, dated 18:00 UTC, projected a 6.5% difficulty reduction around November 13. The mining data platform put current difficulty at 148.36 trillion and spot hashprice at $31.89 per petahash per second per day. Hashprice measures expected daily revenue from a unit of mining capacity, before expenses.

With Bitcoin’s price, block subsidy and average transaction fees per block unchanged, that projected cut would lift hashprice to about $34.11. It would improve the electricity cushion for miners still operating, while leaving a large gap between older equipment and a more efficient S21.

Lower difficulty increases the probability that a given amount of computing work earns a block reward. Expected revenue per unit of work therefore moves inversely with difficulty when the value of rewards stays fixed.

The scenario calculation divides $31.89 by 0.935, the share of difficulty remaining after a 6.5% reduction. That produces a 7% increase and isolates the retarget’s effect. Actual dollar receipts would also depend on Bitcoin pricing and fees.

Bitcoin recalculates difficulty every 2,016 blocks, using block timestamps to target roughly two weeks. November 13 and the size of the cut remain estimates that can change as more blocks arrive.

Older rigs still need cheaper power

The useful operating test is the highest electricity tariff gross mining revenue can cover. Dividing expected daily receipts by the machine’s daily wall-power consumption gives that electricity-only ceiling. A tariff below the ceiling leaves something toward other expenses; a tariff above it means machine electricity alone exceeds gross revenue.

BITMAIN’s S19 specifications list two model 240-Ca variants at 95 and 90 terahashes per second, both drawing a nominal 3,250 watts at 25 degrees Celsius. Its S21 specification lists 200 TH/s at 3,500 watts under the same temperature condition.

The calculations assume continuous operation at nominal ratings and a 6.5% difficulty cut, with Bitcoin price, subsidy and average fees per block unchanged. They exclude pool fees, separate cooling and site loads, repairs, labor, hosting overhead, financing and equipment costs.

Compare electricity coverage before and under the projected cut

At the modeled $34.11/PH/s/day, the S19 still falls short at 5¢/kWh; the S21 barely covers electricity at 8¢/kWh.

Under the projected cut, the older S19 stays below its illustrative power bill; the S21 gains only a thin electricity cushion.

November 13 and the 6.5% cut are projections from the Nov. 9, 18:00 UTC snapshot. Price, subsidy and average fees per block remain fixed. Machine electricity coverage excludes pool fees, separate cooling/site loads, repairs, labor, overhead, financing and equipment costs. Nameplate performance can vary.

Sources and evidence

Sources

1. Hashrate Index, Nov. 9 snapshot
2. BITMAIN S19 specifications
3. BITMAIN S21 specification
4. Bitcoin proof-of-work documentation

Supporting facts

• As of November 9, 2026 at 18:00 UTC, Hashrate Index reported spot hashprice of $31.89 per PH/s/day and current difficulty of 148.36 trillion, with a projected 6.5% difficulty reduction around November 13. [1]
• A 6.5% difficulty reduction would raise expected revenue per unit of computing power by 6.95%, taking a $31.89 per PH/s/day baseline to about $34.11, if Bitcoin price, subsidy and average transaction fees per block remain unchanged. [1] [4]
• BITMAIN’s S19 model 240-Ca has 95 TH/s and 90 TH/s variants, both rated at 3,250 W at 25 C, with hashrate tolerance ±3% and wall-power tolerance ±5%. [2]
• BITMAIN specifies the S21 at 200 TH/s and 3,500 W at 25 C, implying 17.5 J/TH; its retained specification table gives no numeric tolerance. [3]
• Using nominal ratings and continuous operation, the S19 240-Ca 95 TH/s electricity-only ceiling rises from 3.88 to 4.15 cents/kWh under the projected cut, while its 90 TH/s counterpart rises from 3.68 to 3.94 cents/kWh, with Bitcoin price, subsidy and average fees per block unchanged. [1] [2] [4]
• For a nominal 200 TH/s, 3,500 W S21 running continuously, a projected 6.5% difficulty cut would lift the electricity-only ceiling from 7.59 to 8.12 cents/kWh from the November 9 hashprice baseline, if Bitcoin price, subsidy and average fees per block stay unchanged. [1] [3] [4]
• At an illustrative 5 cents/kWh, both modeled S19 240-Ca variants would still earn less than their electricity bill after a projected 6.5% difficulty cut from the November 9 hashprice baseline, if Bitcoin price, subsidy and average fees per block stay unchanged. [1] [2] [4]
• At an illustrative 8 cents/kWh, a nominal 200 TH/s, 3,500 W S21 running continuously would move from below to just above electricity coverage after a projected 6.5% difficulty cut from the November 9 hashprice baseline, leaving about 10 cents/day before other costs if Bitcoin price, subsidy and average fees per block stay unchanged. [1] [3] [4]
• These model-specific electricity ceilings exclude pool fees, separate cooling and site loads, repairs, labor, hosting overhead, financing and equipment costs, and actual performance can differ from nameplate specifications. [2] [3] [1]

Method

Divide Nov. 9 hashprice $31.89 by 0.935: $34.10695/PH/s/day, up 6.95187%. Ceilings = hashprice × TH/s ÷ (24 × watts), in USD/kWh. Bars use a shared 0–10 cents/kWh scale and unrounded inputs; labels round to two decimals. Nominal 95 TH/s/3250 W S19 and 200 TH/s/3500 W S21 run continuously. Tariffs of 5 and 8 cents/kWh are illustrative.

Scope

November 13 and the 6.5% cut are projections from the Nov. 9, 18:00 UTC snapshot. Price, subsidy and average fees per block remain fixed. Machine electricity coverage excludes pool fees, separate cooling/site loads, repairs, labor, overhead, financing and equipment costs. Nameplate performance can vary.

Infographic by CryptoSlate

At an illustrative 5 cents/kWh, both S19 variants would still earn less than their electricity bill after the cut. A nominal S21 paying 8 cents/kWh would move from below to just above electricity coverage, leaving a thin cushion of about 10 cents a day before other costs. The two tariffs are illustrative.

The comparison uses each model’s stated power and hashrate. Actual machines can differ: BITMAIN gives the S19 variants hashrate tolerance of plus or minus 3% and wall-power tolerance of plus or minus 5%. The S21 specification gives no numeric tolerance. Each ceiling applies to the specific model and nominal settings shown.

CryptoSlate’s October 14 analysis modeled the electricity squeeze from a projected difficulty increase, while its November 4 report examined a forward market implying little additional mining competition.

The next test is the completed adjustment and hashprice afterward. At the November 9 inputs, the projected cut would expand electricity coverage. Whether that becomes a viable operating margin depends on the actual revenue rate, equipment performance and costs beyond the machine’s power draw.