Power Consumption Of Server Calculator

Work out power consumption of server instantly with clear inputs, formula shown and shareable results.

About Power Consumption Of Server Calculator

Server power scales roughly linearly between idle and maximum with utilisation, but idle draw is the striking figure: at 120 W idle against 480 W peak, a server at 45 percent utilisation still spends most of its energy simply being switched on. That poor energy proportionality is the strongest argument for consolidation and for powering down idle capacity.

Formula

Server power

average watts = idle + (max - idle) x utilisation; annual kWh = watts x 8766 / 1000; cost = kWh x price

Worked example

With the default values below, Power Consumption Of Server Calculator returns Average power draw of 282. Change any input above and every figure here is recalculated in your browser.

Inputs used

Idle power drawminimum 1 W: 120 W
Maximum power drawminimum 1 W: 480 W
Average CPU utilisationaccepts 0–100 %: 45 %
Electricity price per kWhminimum 0: 0.18

Results

Average power draw: 282 W
Annual energy consumption: 2,472 kWh
Annual electricity cost: $444.96
Share of power drawn at idle: 42.6%

Step by step

1Values used
2Server power
3Average power draw= 282 W
4Annual energy consumption= 2,472 kWh
5Annual electricity cost= 444.96
6Share of power drawn at idle= 42.6

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why is idle draw so high?

Fans, memory refresh, chipset and power supply conversion losses continue regardless of load. Modern platforms are better but far from proportional.

Does the power supply rating matter?

Yes. A supply is most efficient near half load, so a heavily oversized supply wastes energy. Titanium-rated units hold high efficiency across a wider range.