// blog · · by Nathan Baldwin
// How much does a Bitaxe Gamma actually pull from the wall? Real Kill-a-Watt measurements at stock and overclock, plus monthly power cost math.
A Bitaxe Gamma at stock settings pulls 14.3W from the wall on average. Mine three of them and you’re at 43W — less than a single old incandescent bulb. At the US average $0.16/kWh, three Gammas cost about $5 per month in electricity. The dashboard reports lower numbers because it only counts the chip; the wall plug is what your power company bills.
If you’ve been doing your ROI math from AxeOS’s reported wattage, you’re underestimating by ~15%.
AxeOS shows a “Power” reading on the dashboard. That number is the BM1370’s calculated power draw — voltage × current, measured at the chip’s input. For a stock Gamma, that reads ~12W.
The actual wall draw is higher because there’s overhead the dashboard doesn’t see:
Add those up and you’re at ~14.3W actual wall draw for a 12W chip — about 19% overhead. The dashboard’s number is useful for tuning efficiency between chips. It’s not the number to use for your electric bill.
I plugged a Kill-a-Watt P3 P4400 meter inline with each of three Gammas over a week. All values are 7-day averages with the fan profile on auto, in a 22°C ambient room.
Stock (525 MHz / 1166 mV) - AxeOS power: 12.0W - Wall power: 14.3W - Wall hashrate: 1.20 TH/s - True efficiency: 11.9 J/TH
Light OC (550 MHz / 1180 mV) - AxeOS power: 13.1W - Wall power: 15.5W - Wall hashrate: 1.27 TH/s - True efficiency: 12.2 J/TH
Sweet spot (575 MHz / 1200 mV) - AxeOS power: 14.4W - Wall power: 17.0W - Wall hashrate: 1.35 TH/s - True efficiency: 12.6 J/TH
Aggressive (625 MHz / 1250 mV) - AxeOS power: 17.2W - Wall power: 20.3W - Wall hashrate: 1.50 TH/s - True efficiency: 13.5 J/TH
The wall-to-AxeOS delta stays remarkably constant across all four tiers — about 2.3W to 3.1W of overhead. The overhead is mostly fixed cost (ESP32, OLED, conversion loss), so as you push the chip harder, the overhead becomes a smaller percentage. At stock it’s 19% of wall draw, at aggressive it’s 15%.
That means efficiency from the wall’s perspective actually improves slightly as you overclock, until the chip itself starts becoming less efficient. The crossover happens around Tier 3.
A Gamma running 24/7 at stock pulls:
14.3W × 24h × 30 days = 10,296 Wh = 10.3 kWh/month
At various US electricity rates:
At sweet-spot tune (17W):
At aggressive tune (20.3W):
For a 5-Gamma fleet at sweet-spot tune in a US-average state, you’re looking at ~$10/month in electricity. Compared to ~$30/month in expected mining revenue at current BTC price and difficulty, that’s a positive operating margin — though not by enough to recover the hardware cost quickly.
A Gamma at 17W dumps 17W of heat into the room. That doesn’t sound like much, but six of them on a shelf produces ~100W of waste heat — roughly equivalent to a tower PC at idle. Over a day, that’s 2.4 kWh of heat energy added to your room.
In winter, this is free heat that offsets your heating bill. In summer, in a state where you run air conditioning, you’re paying for that heat twice — once to generate it, once to remove it. AC at typical efficiency adds roughly 30% to the operating cost during cooling months.
People rarely do this math. If you live somewhere with seasonal AC, your effective Bitaxe operating cost during summer is 30% higher than the napkin number. Worth knowing if you’re sizing a fleet.
The 5V supply matters more than people realize. A cheap 25W charger brick is 80-85% efficient at part load. A name-brand 65W USB-C PD charger is 92-94% efficient.
The difference: a Bitaxe pulling 14.3W at the wall behind an 85% brick is pulling ~16.8W upstream of the brick. Behind a 93% brick, it’s ~15.4W. Over a year on US-average power, that’s a $2.70 difference per device. Not life-changing on one device. Adds up across a fleet.
If you’re already buying 5+ Bitaxes, a single USB-C hub with PD passthrough is more efficient than 5 individual wall warts. Anker, Ugreen, and others sell 65-100W USB-C PD hubs that can power 4-5 Gammas off one outlet at ~92-94% conversion efficiency. Cabling is also cleaner.
Plug a Kill-a-Watt or smart plug with energy monitoring (TP-Link Kasa, Aqara, etc.) inline with your Bitaxe for a week. Note the average wattage. Multiply by 24, by 30, by your $/kWh rate from your electric bill. That’s your real monthly cost.
If you’re using AxeOS’s reported wattage in your ROI calculations, add 15-20% overhead. If you’re shopping for a power brick to add Bitaxes to a fleet, spend the extra $15 on a name-brand PD hub — the efficiency pays back inside a year.
Try it yourself: Bitaxe Baller is a free Mac app that surfaces these recommendations automatically across your fleet — live monitoring, tuning suggestions, pool config, all in a native window. Open source on GitHub.