How much does an air purifier cost per month in Montana?

About $5.47 a month, assuming 50 W, 24 hours a day, 365 days a year at 14.99¢/kWh.

How many kilowatt-hours does an air purifier use?

Roughly 438 kWh a year under these assumptions, or 0.05 kWh for every hour it runs.

Is that expensive compared with other states?

Montana has the 14th cheapest average residential rate in the country, so this appliance costs less here than the U.S. average of $80.20 a year.

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Cost to run an air purifier in Montana (July 2026 rates)

At 14.99¢ per kilowatt-hour — Montana's average residential price in July 2026 — running an air purifier costs $65.66 a year. That is 18% less than the national average of $80.20. Montana's residential rate is up 5.0% from July 2025, which moves this appliance from $62.50 to $65.66 a year.

Per hour: 0.7¢
Per day of use: 18.0¢
Per month: $5.47
Per year: $65.66

Assumption: 50 W, 24 hours a day, 365 days a year — 438 kWh a year. Mid-size HEPA unit on medium. High speed can triple the draw. Use the calculator to swap in the numbers from your own model.

How Montana compares

Montana pays 14.99¢/kWh, the 14th cheapest residential electricity of the 51 U.S. jurisdictions EIA reports. For this appliance that works out to $14.54 less a year than the typical U.S. household pays for the same use. Running the same air purifier costs $55.71 a year in Louisiana and $210 in Hawaii, so where you live changes this bill by $155 a year.

State	Rate	Per month	Per year
Mississippi	14.54¢	$5.31	$63.69
Washington	14.71¢	$5.37	$64.43
Montana	14.99¢	$5.47	$65.66
Florida	15.03¢	$5.49	$65.83
North Carolina	15.16¢	$5.53	$66.40

States ranked by average residential price, cheapest first. See all 51 states for an air purifier.

What else costs about the same in Montana

Refrigerator$59.96 a year in MT Desktop computer$59.96 a year in MT Dehumidifier$80.95 a year in MT

Cutting the number down

Right-sizing to the room lets you run a bigger unit on low instead of a small one on high, which is quieter and cheaper for the same clean-air delivery.
A loaded filter forces the fan to work harder for less airflow, so late-life filters cost more per unit of clean air.

Questions

How much does an air purifier cost per month in Montana?: About $5.47 a month, assuming 50 W, 24 hours a day, 365 days a year at 14.99¢/kWh.
How many kilowatt-hours does an air purifier use?: Roughly 438 kWh a year under these assumptions, or 0.05 kWh for every hour it runs.
Is that expensive compared with other states?: Montana has the 14th cheapest average residential rate in the country, so this appliance costs less here than the U.S. average of $80.20 a year.