Quick facts
- Typical draw: 5โ15 W on low, 50โ70 W on high for a room-size unit
- Electricity, 24/7: about $45 a year at 30 W and $0.17/kWh
- Filters: $40โ$80 per replacement, usually once a year
- Energy Star units: roughly 40 percent more clean air per watt
Running a room air purifier around the clock costs about $45 a year in electricity.
That is a little under $4 a month.
Most people guess three or four times higher before they do the math.
The reason the number is small is simple. A purifier is a fan, not a heater.
Nothing inside it produces heat on purpose, and heat is what makes an appliance expensive.
The bill comes down to three numbers
Watts, hours, and your local rate. That is the whole calculation.
Multiply watts by hours, divide by 1,000, multiply by the price per kilowatt-hour.
A 30-watt unit running all day uses 0.72 kWh.
Across a year that is roughly 263 kWh.
At the current US residential average of about $0.17 per kWh, that lands near $45.
Your own rate matters more than the machine. Hawaii and California readers can double that figure; Louisiana and Idaho readers can nearly halve it.
The wattage you want is on the back label or in the manual, not on the retail page.
Beware the figure advertised as "maximum" โ that is the highest fan speed, which almost nobody runs continuously.
Smart models report live draw in the app, which is the easiest way to check your own unit.
Fan speed is the only lever that really moves it
Everything else is rounding. Speed is not.
On low, many room units draw 5 to 15 watts โ less than a single old-style bulb.
On high, the same machine can pull 50 to 70 watts.
Over a year of continuous use, that is the gap between about $12 and about $89.
Which points to a cheaper habit than most people run.
A correctly sized purifier left on low all day costs less than one takeout coffee a month.
Sizing the unit up and running it slowly beats sizing it down and running it hard.
You get the same clean-air delivery, a quieter room, and a smaller bill.
Filters cost more than the electricity does
The recurring expense people forget is not power. It is the cartridge.
A true HEPA-plus-carbon replacement runs $40 to $80 for most popular models.
Manufacturers generally ask for one a year. Heavy use, pets, or wildfire season pull that closer to six months.
So the sticker price on the box is only the first payment.
Before you buy, look up the filter part number and what it actually sells for.
A $120 purifier with an $80 annual filter is more expensive over three years than a $200 one with a $35 filter. We ran those numbers for a mid-range model in our Levoit Vital 200S-P review.
Energy Star narrows the field, but not the way you think
Energy Star certifies room air cleaners on clean-air delivery per watt, not on total consumption.
A certified unit produces roughly 40 percent more clean air for the same power draw as an uncertified one.
That makes the label useful as a tiebreaker between two models with similar CADR ratings.
Look Up Certified Room Air CleanersOfficial ENERGY STAR product finder โ
What the label will not tell you is the filter price. No efficiency rating covers consumables.
Bottom line: Electricity is the cheap part of owning an air purifier. Budget for the filter, size the unit generously, and leave it on low.
Read the EPA Guide to Home Air CleanersU.S. Environmental Protection Agency โ
