How much does a dehumidifier cost to run?
At the current average residential rate of 18.34¢ per kWh, a typical 500 W dehumidifier costs about 9¢ per hour — around $16.69 a month and $200 a year at 42 hours a week.
The rate and formula behind these numbers
kWh = watts × hours ÷ 1,000, and cost = kWh × rate. The yearly figure assumes the same weekly pattern all year (× 52); the monthly figure is the yearly one ÷ 12.
Electricity rate: 18.34¢ per kWh — the US EIA Electric Power Monthly for June 2026, the latest month EIA has published (US average across all states). Source: US EIA Electric Power Monthly. Checked September 2, 2026. It excludes the fixed monthly customer charge, which you pay regardless of use.
A basement dehumidifier is the classic case of a modest draw adding up, because it is the hours that get you rather than the wattage — it works whenever the air is damp, which in a humid summer is most of the day. A larger capacity unit pulls more power while running but reaches the target faster and then idles, so it often costs less over a season than a small one grinding away. Set a humidistat and let it stop; running one against an open window is paying to dry the outdoors.