An Antminer KS5 Pro mining Kaspa this morning earns about £3.17 a day after pool fees. It consumes 75.6 kWh doing it. That puts the break-even electricity price at 4.19 pence per kilowatt hour, against a UK price cap of 26.11p and an Octopus Agile median today of 29.78p. Electricity costs roughly seven times what the machine can pay for it.
Not a close call. A factor of seven.
The machine
Bitmain lists one configuration: 21 TH/s at 3,150 W, or 150 J/TH, on kHeavyHash. There is no second bin. The plain KS5 is a different product at 20 TH/s and 3,000 W, and mixing the two is the standard error here, because both are 150 J/TH and only the hashrate and wattage pair separates them.
The tolerances are worth quoting because nobody does. Bitmain allows ±3 per cent on hashrate and ±5 per cent on power, so a unit at both unfavourable extremes gives 20.37 TH/s for 3,307 W — 162 J/TH, 8 per cent worse than the box.
| Hashrate and power | 21 TH/s at 3,150 W |
| Efficiency | 150 J/TH (162 J/TH at worst tolerance) |
| Network hashrate | 323.4 PH/s |
| Share of network | 1 in 15,402 |
| Hashprice, net of 1% pool fee | £0.1507 per TH per day |
| Revenue, net of pool fee | £3.17 per day |
| Consumption | 75.6 kWh per day |
| Break-even electricity | 4.19 p/kWh |
| Revenue per MW | £1,005 per day |
| Net at the Agile median | −£19.35 per day |
| Net at the cheapest Agile half-hour | −£8.00 per day |
Read the last two rows. Running only during the cheapest half-hour published today, at 14.77p, still loses eight pounds a day. There is no window in the UK tariff structure where this works.
Why the numbers moved
Kaspa’s network hashrate is 323.4 PH/s, down 79.8 per cent from its January 2025 peak and 23.6 per cent year on year. A falling network raises revenue per terahash, because the emission is split fewer ways.
That is not good news, it is the symptom. Hashrate falls because miners switch off, and miners switch off because the power bill stopped being covered. Nor is the gain what it looks like. Kaspa cuts its block reward about 5.6 per cent every month, compounding to a full halving each year, and the next step is 5 October 2026. Emission has fallen by roughly two thirds since January 2025, so a fivefold gain from the shrinking network nets down to about 56 per cent more KAS per terahash — and in sterling, to a decline.
A network shedding four fifths of its hashrate is what capitulation looks like from the inside.
The case against, in practical terms
It has been superseded. The Antminer KS7 runs 40 TH/s on 3,080 W — 90 per cent more hash for slightly less power — and on the same live data its break-even is 8.16p, nearly double. A better machine, still under water at every UK domestic tariff.
Resale is brutal. New UK stock sits between £1,150 and £1,884 depending on VAT treatment, and both UK sellers we checked are out of stock. Tested working units are meanwhile changing hands on eBay at £148 to £244, with 23 sold on one listing. The secondary market values this machine at roughly 8 to 21 per cent of UK retail, and the sellers are American mining operations clearing floor space.
It will not run on a normal socket. At 230 V it draws 13.7 A before tolerance, and Bitmain specifies a 20 A input and a 4,000 W supply. A 13 A plug is not adequate; this needs a dedicated circuit and an electrician. It also makes 76 dBA continuously — a petrol lawnmower running in your house forever — and 3,150 W of heat, which can push a room past the 40 °C operating ceiling.
The warranty runs 365 days from Bitmain’s shipment date, not your purchase date, so on a machine launched in early 2024 it may already have expired. The nearest repair centre is Amsterdam and you pay the customs. Bitmain scores 1.4 out of 5 on Trustpilot.
The case for
There is one, and it is narrow. Meaningful solar you cannot export profitably, an industrial supply contract, or a real need for 3.15 kW of winter heat in a ventilated outbuilding all change the arithmetic. At second-hand prices the capital cost is trivial, which is the strongest argument available.
But then you are buying a very loud space heater that earns three pounds a day. A £30 convector does the heating without the circuit, the noise or the Kaspa price risk. For a UK domestic buyer at retail this machine cannot be run at a profit, and the gap is not close.
Sources, retrieved 7 September 2026: Bitmain’s KS5 Pro, KS5 and warranty pages; api.kaspa.org for hashrate, block reward and halving schedule; CoinGecko for the KAS price (£0.02611113 at 10:43 UTC); the Octopus Agile Eastern England API; Ofgem; the UK Integrated Online Tariff API; the IET wiring forum; eBay; Trustpilot. Every profitability figure was derived here in python3 from network data, never a mining calculator, and our emission figure reconciles exactly with Kaspa’s chromatic schedule — the check confirming ten blocks per second is live. Only 44 of 48 half-hourly Agile rates had been published. Contested: KS7 specifications come from resellers, not Bitmain, and the KS7 is itself sold in several bins; the hashrate history behind the 79.8 and 23.6 per cent falls rests on a single API series; and reseller prices span an eightfold range. KAS rose 17 per cent in the preceding 24 hours, so these figures are timing-sensitive. Not a recommendation to buy anything; mining receipts are taxable.