This self-hosted energy calculator adds up what your homelab really draws from the wall. Pick your hardware
across four tiers, from a single Raspberry Pi to a stack of AI GPUs, set how many of each you run, and watch
the totals update live: watts, monthly kWh, electricity cost, and yearly CO2.
Compute
25 W
Raspberry Pi 4idle 3 W · load 7 WTom's Hardware, measured at wall
0
Raspberry Pi 5idle 3 W · load 10 WTom's Hardware, measured at wall
The estimate is deliberately simple: a flat price per kWh (no tiered or time-of-use tariffs), no PSU
conversion losses, a 730 hour month, and no datacenter overheads like PUE or embodied carbon. Systems are
counted as whole-box wall power; GPU cards are counted as card-only draw on top of a host system, at stock
power limits. Real inference rigs often run power-limited, an RTX 3090 capped to about 275 W loses almost no
tokens per second, so the load numbers here are the ceiling, not the floor. The duty cycle assumes your gear
runs 24/7, idling most of the day; move the slider if your machines work harder. Measured wall numbers from a
Kill-A-Watt or a smart plug always beat any preset.
The maths
Daily kWh = (idle W × idle hours + load W × load hours) ÷ 1000
Monthly kWh = daily kWh, scaled to a 730 hour month
Cost = monthly kWh × your price per kWh
CO2 = yearly kWh × your grid intensity
Sources
Electricity prices: household averages in USD, Eurostat 2025.
Grid CO2 intensities: Ember.
Device wattages: the source under each row in the list.