Home AI Rig Electricity Cost Calculator
Generic PC power calculators assume a gaming rig that sleeps at night. This assumes a GPU running inference around the clock, because that's what a home AI box actually does. Enter your setup to see the real daily, monthly, and yearly cost. Nothing uploaded.
Energy Use
Cost
Full cost breakdown
Note
This estimate covers GPU power only - it does not include CPU, motherboard, storage, cooling fans, or PSU efficiency losses, which typically add 15-30% on top. Check your wall-measured draw with a power meter for a more accurate figure.
Learn more: what a home AI rig costs to run
How the daily energy figure is built
The calculator splits each 24 hour day into hours at load and idle hours. For each GPU it adds load watts times load hours and idle watts times idle hours, multiplies by the number of GPUs and divides by 1,000 to get kWh. Two GPUs idling at 20 W for 20 hours and running at 300 W for 4 hours use 2 x (300 x 4 + 20 x 20) / 1,000 = 3.2 kWh a day.
Monthly and annual figures multiply the daily number by 30 and 365. At $0.15 per kWh, that rig costs $0.48 a day, $14.40 a month and about $175 a year.
When idle draw matters
In that example the load hours still dominate: 2.4 kWh against 0.8 kWh for idling. Idle energy only overtakes load energy when the rig works for very little of the day. With these wattages the two are equal at 1.5 hours of load per day, because 300 x 1.5 = 450 Wh matches 20 x 22.5 = 450 Wh per GPU.
A rig used for half an hour a day uses about 150 Wh at load and 470 Wh idling per GPU, so more than three quarters of its energy goes to doing nothing. For a mostly idle rig, lowering idle draw saves more than lowering load draw.
What the calculator leaves out
It counts GPU wattage only. The CPU, motherboard, fans, drives and power supply losses add to the wall draw, so enter the figure you measure at the wall where you can. A plug-in power meter between the wall and the PC is the most reliable way to read both idle and load watts.
FAQ
Does power-limiting a GPU cut the cost?
Lowering the power limit lowers load draw, and the effect on speed depends on your workload, so measure both. Enter the new wattages in the calculator to see the difference in cost.
How do I find my rig's idle wattage?
Use a plug-in power meter. Manufacturer TDP figures describe maximum power under load, not what the card uses at rest, so they cannot tell you the idle number.
When is self-hosting cheaper than a cloud API?
It depends on how many hours the rig works, its idle draw and the cost of the hardware. A rig that mostly sits idle pays for electricity all day, so use the calculator's annual figure next to what the same requests would cost on an API.