PLAN THE RUNNING COST

What does your home server cost to leave on?

Estimate electricity use with separate idle and active power figures. It is a simple planning tool for mini PCs, old desktops, NAS-style builds and other always-on systems.

Use measured power where possible. A CPU or power-supply rating is not the same as the electricity drawn by the whole server. Plug-in energy meters give a much better input.

Your server

Idle power (W)Measure the whole system at the wall if you can.Active power (W)Use a realistic working load, not the power-supply rating.Active hours per dayThe remaining hours are calculated at idle power.Days per month30 is a simple monthly planning assumption.Electricity price (p / kWh)Enter the unit rate from your own tariff.

ESTIMATED RUNNING COST

Around £2.85 per month

£34.68 / year

Energy per day: 0.38 kWh
Energy per month: 11.4 kWh
Energy per year: 138.7 kWh
Idle hours per day: 20

This assumes the server remains switched on for 24 hours a day and spends the non-active hours at your idle power figure.

What this estimate includes

Idle time matters

A home server may spend most of its life waiting. A low idle draw can matter more than a dramatic peak figure.

Storage changes the total

Extra disks, external enclosures and network equipment use power too. Include them if they are part of the server setup you are comparing.

Your tariff is the key input

The default 25p per kWh is only an editable example. Use the electricity unit rate you actually pay.

This is an energy-cost estimate, not a total cost of ownership. Hardware purchase, replacement disks, backups, internet access and your time are separate.