How much does a desktop computer cost per month in California?

About $11.58 a month, assuming 200 W, 8 hours a day, 250 days a year at 34.74¢/kWh.

How many kilowatt-hours does a desktop computer use?

Roughly 400 kWh a year under these assumptions, or 0.20 kWh for every hour it runs.

Is that expensive compared with other states?

California has the 2nd most expensive average residential rate in the country, so this appliance costs more here than the U.S. average of $73.36 a year.

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Cost to run a desktop computer in California (June 2026 rates)

At 34.74¢ per kilowatt-hour — California's average residential price in June 2026 — running a desktop computer costs $139 a year. That is 89% more than the national average of $73.36. California's residential rate is up 3.4% from June 2025, which moves this appliance from $134 to $139 a year.

Per hour: 6.9¢
Per day of use: 55.6¢
Per month: $11.58
Per year: $139

Assumption: 200 W, 8 hours a day, 250 days a year — 400 kWh a year. An office-class tower plus monitor, doing ordinary work. Use the calculator to swap in the numbers from your own model.

How California compares

California pays 34.74¢/kWh, the 2nd most expensive residential electricity of the 51 U.S. jurisdictions EIA reports. For this appliance that works out to $65.60 more a year than the typical U.S. household pays for the same use. Running the same desktop computer costs $52.44 a year in Nevada and $211 in Hawaii, so where you live changes this bill by $158 a year.

State	Rate	Per month	Per year
New York	29.49¢	$9.83	$118
Maine	29.59¢	$9.86	$118
Massachusetts	29.61¢	$9.87	$118
California	34.74¢	$11.58	$139
Hawaii	52.72¢	$17.57	$211

States ranked by average residential price, cheapest first. See all 51 states for a desktop computer.

What else costs about the same in California

Refrigerator$139 a year in CA Air purifier$152 a year in CA Electric oven$116 a year in CA

Cutting the number down

Sleep after 15 minutes idle is the default with the largest payoff and the smallest downside.
Screensavers do not save energy; a display running a 3D animation costs more than a blank screen.

Questions

How much does a desktop computer cost per month in California?: About $11.58 a month, assuming 200 W, 8 hours a day, 250 days a year at 34.74¢/kWh.
How many kilowatt-hours does a desktop computer use?: Roughly 400 kWh a year under these assumptions, or 0.20 kWh for every hour it runs.
Is that expensive compared with other states?: California has the 2nd most expensive average residential rate in the country, so this appliance costs more here than the U.S. average of $73.36 a year.