How much does a desktop computer cost to run in California?
$10 a month
- A day of use
- $0.33
- An hour of running
- $0.04
- A year
- $121.73
120 W, 8 hours a day (tower only, no monitor), at California’s average rate of 34.7¢ per kWh (EIA, June 2026). How we calculate this
Change the watts, hours or rate
What it costs at other usage levels
| Use | A day | A month | A year |
|---|---|---|---|
| 1 hour a day | $0.04 | $1.27 | $15.22 |
| 2 hours a day | $0.08 | $2.54 | $30.43 |
| 4 hours a day | $0.17 | $5.07 | $60.86 |
| 8 hours a day typical | $0.33 | $10.14 | $121.73 |
| 24 hours a day | $1.00 | $30.43 | $365.19 |
A typical model draws about 120 W (Virginia Cooperative Extension).
California compared with other states
California’s residential rate is the 2nd most expensive of 51 states and DC, 16.4¢ above the US average of 18.3¢ (+89%). California’s rate is up 1.2¢ from June 2025 (33.6¢, +3.4%).
A cheaper way to do the same job
- A laptop for the same hours would cost $4.23 a month, saving $5.92 a month and $71.01 a year.
Ways to spend less
- Set it to sleep after 15 minutes idle.
- Shut it down at night instead of leaving it on.
- For email and browsing, a laptop does the same job on much less power.
Questions
How much does it cost to run a desktop computer per hour?
About $0.04 an hour in California. A desktop computer at 120 W uses 0.120 kWh per hour, and at California’s average of 34.7¢ per kWh that comes to $0.04.
How much does a desktop computer add to your electric bill?
Used 8 hours a day (tower only, no monitor), about $10.14 a month in California, or $121.73 a year.
How much does it cost to run a desktop computer 24 hours a day?
Running nonstop, a desktop computer would use 2.88 kWh a day and cost $1.00 a day, or $30.43 over an average month in California.
How many watts does a desktop computer use?
A typical model draws about 120 W (Virginia Cooperative Extension). Check the label on yours: cost scales directly with watts, so a 20% lower wattage means a 20% lower bill.
Is it cheaper to run a desktop computer or a laptop?
Using a laptop for the same hours instead would cost about $4.23 a month instead of $10.14, saving $5.92 in California.
Why does a desktop computer cost more or less to run in California than elsewhere?
California’s residential rate is the 2nd most expensive of 51 states and DC, 16.4¢ above the US average of 18.3¢ (+89%). California’s rate is up 1.2¢ from June 2025 (33.6¢, +3.4%). The appliance uses the same energy everywhere; only the price per kWh changes.
Sources
- Virginia Cooperative Extension: Estimating appliance and home electronic energy use (reproduces U.S. Department of Energy sample wattages)
- Penn State EGEE 102: Typical range of power consumption (wattage)
- U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A: average price of electricity to ultimate customers, residential, June 2026 Figures transcribed from republications of this table on September 26, 2026; pending direct verification from the EIA API.
- Carrier page: June 2026 residential average price, citing EIA Electric Power Monthly Table 5.6.A
Usage assumptions (hours a day, season) are ours and listed on the methodology page. Found an error? Tell us.