Methodology & data sources
HomelabWatts combines two datasets: a hand-curated database of idle and load power draw for
common homelab hardware, and reference residential electricity prices per kWh by region.
Running costs are computed with the standard formula W ÷ 1000 × hours × days × price.
Wattage figures are estimates compiled from manufacturer specifications and community wall-meter
measurements — they are labelled as typical, not guaranteed, and your exact draw will vary with
configuration, firmware and attached storage.
Data sources
| Source | Refresh cadence | License |
|---|---|---|
| HomelabWatts wattage database (curated) | monthly | CC BY 4.0 |
| U.S. EIA — Average Price of Electricity to Ultimate Customers | monthly | Public domain (U.S. Government) |
| Eurostat — Electricity prices for household consumers (nrg_pc_204) | annual | CC BY 4.0 |
How the wattage database is curated
Each device entry records a typical idle and load figure in
watts. We start from manufacturer "access" / "power consumption" specifications where published,
then cross-check against community measurements (r/homelab, ServeTheHome forum threads, and
published wall-meter reviews). Where sources disagree we use a conservative mid-range value and
note the caveats on each device page. We deliberately avoid nameplate PSU ratings and CPU TDPs,
which overstate real-world draw. The database is versioned in src/data/devices.json
and reviewed roughly monthly via scripts/fetch-data.mjs.
How electricity prices are sourced
US prices are residential averages from the U.S. Energy Information Administration (EIA) Electric
Power Monthly. European prices are household-consumer prices (including taxes) from Eurostat.
These are rounded reference values for estimation, stored in
src/data/kwh-presets.json with the date they were captured — they are not your exact
tariff. Always check your own bill for the precise per-kWh rate.
How calculations work
Energy use is power in kilowatts (watts ÷ 1000) multiplied by hours of use, giving kilowatt-hours (kWh). Cost is kWh multiplied by your price per kWh. The "typical 24/7" figure used in summary tables weights idle 70% and load 30%, reflecting that always-on homelab hardware spends most of its time near idle. The optional CO₂ estimate multiplies annual kWh by a grid carbon intensity (default 400 g/kWh, near the world average). All calculators run client-side; we do not store your inputs.
Limitations
Every figure is an estimate and may lag the underlying source or contain errors. Wattage varies with hardware revision, BIOS settings, drive count and ambient temperature; prices exclude fixed standing charges. Always verify against a real wall-meter measurement and your own bill before relying on these figures. See our disclaimer.
Last updated: 2026-06-13