Homelab power cost calculator
To estimate what a homelab device costs to run, multiply its average power draw (watts) by the
hours it runs per day, then by your electricity price per kWh: cost/year = W ÷ 1000 ×
hours × 365 × price. For example, a device averaging 50 W running 24/7 uses about
438 kWh/year — roughly $74 at the US average of $0.17/kWh
or about €175 in Germany. Enter your own numbers below for an instant monthly, annual and CO₂
estimate.
Source: EIA / Eurostat electricity prices. Data as of 2026-06-01.
Quick reference: annual cost of running 24/7
| Average draw | US ($0.17) | Germany (€0.40) | UK (£0.25) |
|---|---|---|---|
| 10 W | $14.89 | €35.04 | £21.90 |
| 25 W | $37.23 | €87.60 | £54.75 |
| 50 W | $74.46 | €175.20 | £109.50 |
| 100 W | $148.92 | €350.40 | £219.00 |
| 250 W | $372.30 | €876.00 | £547.50 |
Source: rates from electricity price presets. Costs are estimates and exclude standing charges and taxes that vary by tariff.
How the formula works
Power in watts divided by 1000 gives kilowatts. Multiply by hours of use to get kilowatt-hours (kWh) — the unit your utility bills. The calculator assumes a 30.4-day average month so the monthly and annual figures stay consistent. The optional CO₂ output multiplies annual kWh by your grid's carbon intensity.
Frequently asked questions
What watts should I enter — idle or load?
Use the device's average draw over a day. Most always-on homelab gear sits near idle, so a value a little above idle is usually realistic. For the most accurate figure, measure with a plug-in energy meter (a 'Kill A Watt' type device).
How do I find a device's wattage?
Check our wattage database, the manufacturer spec sheet, or measure it at the wall. Spec-sheet 'maximum' figures are usually far higher than real-world draw.
Does the calculator account for the power supply?
If you enter watts measured at the wall, PSU losses are already included. If you enter component TDPs, add roughly 10-20% for PSU inefficiency.
How is the CO2 figure calculated?
Annual kWh multiplied by your grid's carbon intensity in grams of CO2 per kWh. The 400 g/kWh default is near the world average; your real intensity depends on your region and time of day.
Last updated: 2026-06-13