How much does a 100 W office PC cost to run? Fleet energy calculation

A 100 W office PC running 8 hours a day at 60% load costs about $31.54 a year at $0.18/kWh, $2.63 a month. That's 175 kWh annually; at scale (say 500 seats) it's 87,600 kWh and $15,770 a year, which is when enterprise IT starts caring about specifying efficient Mini PCs instead of full towers.

Annual cost

$32

At $0.18/kWh

Monthly cost

8 h/day at 60% load

Annual consumption

175 kWh

100 W rated

Device Configuration

Device Preset

Max Power Consumption (Watts)

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Utilization: 60%

Effective Power: 60W

Usage per Day (Hours)

Hours

Electricity Price ($/kWh)

$/kWh

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Daily Cost

$0.09

Monthly Cost

$2.59

Yearly Cost

$31.54

175 kWh / year

How this is calculated

A "100 W" office PC is the PSU rating, actual desktop draw for light office work is typically 25-45 W with occasional bursts to 70 W during compiles or video calls. The 60% utilisation figure here is calibrated to capture that mix across an 8-hour day, including lunch and meetings where the machine is mostly idle. Aggressive sleep policies can reduce this further, though in a business context the trade-off with user productivity typically keeps machines awake.

Verdict

$32 per year per seat is trivial individually but compounds quickly at scale. For 1000+ seat fleets, switching from 100 W towers to 45 W thin-client Mini PCs is a $17k/year operating expense cut on electricity alone.