How much electricity does an air purifier use?
A certified room air purifier uses 152 kWh a year - about $28 at the US average tariff. That is the median of 241 certified models, and it ranges from 85 kWh for a small room to 388 kWh for a large one.
But the figure carries an assumption that nobody quoting it mentions: it is calculated on 16 hours of operation a day, not around the clock. The two questions people actually ask - both of them in Google's own suggestion box - are about running one 24/7.
- How much electricity does an air purifier use per year?
- 152 kWh a year. That is a rating figure: it assumes a set amount of use rather than measuring yours. At 14¢ per kWh that is about $21.28 a year.
- How much electricity does an air purifier use per month?
- About 13 kWh a month, which is the yearly figure divided by twelve. There is no separate monthly measurement: the certification tests a year of defined use.
- How much electricity does an air purifier use per day?
- About 0.42 kWh a day, the yearly figure spread over 365 days. It is not the nameplate wattage multiplied by 24: an appliance certified this way draws its rated power only part of the time, and multiplying by 24 hours overstates the real figure several times over.
Work it out with your own tariff
Residential sector, US average, as published in Electric Power Monthly released 26 August 2026. This is a revenue-weighted average across all residential customers and utilities, not a tariff any single household pays. In the same month the state residential averages (table 5.6.A) ran from 14.37 cents in Idaho to 52.72 in Hawaii, with California at 34.74 and New York at 29.49 — a spread of more than three and a half times. Use the figure from your own bill; the default here is a placeholder, not an answer.
Your rate, cents per kWh
There is no hours setting here, unlike the other device pages. This appliance is not certified in watts at all — only as a yearly total, and that total already includes a defined pattern of use. Multiplying it by hours of your own would count the usage twice.
| Period | Cost | Where it comes from |
|---|---|---|
| A year | $21 | 152 kWh — the measured figure |
| A month | $1.77 | a twelfth of the year |
| A day | $0.06 | a 365th of the year |
152 kWh × 14¢ = $21 a year. That averages 17 W drawn continuously.
152 kWh a year is the median of 241 certified room air cleaners. The published figure assumes 16 hours of active operation per day, which the programme states in the data itself; working backwards from the certified figures gives 5,840 hours, and 16 x 365 = 5,840. The same programme puts a standard, uncertified room air cleaner at 394 kWh a year - but that one is quoted for continuous operation, so the two are not measured on the same day. Rate defaults to 18.34¢ (U.S. Energy Information Administration, June 2026) — a national average, which is wrong for you specifically, so put your own in above.
The certified figure assumes sixteen hours a day
Every answer you will find is in watts: 20 to 100, 30 to 100, 30 to 250, "around 50 on average". None of them multiplies by anything, so none of them is an answer to what it costs.
There is a published annual figure, and the agency states its assumption in one line: this is the annual energy use assuming 16 hours of active operation per day.
That matters more than usual here, because the two questions people actually ask - both of them sit in Google's own "people also ask" box - are "how much does it cost to run an air purifier 24/7?" and "is it expensive to run one all day?" The label answers a sixteen-hour question. Nobody quoting it says so.
Sixteen hours a day is 5,840 hours a year. Working backwards from the certified figures of 241 models gives 5,840 hours to within a few percent - the arithmetic and the stated definition agree, which is the only reason this page states it.
What it costs on the label's own terms
| Room size | Middle half | Median | Models |
|---|---|---|---|
| Up to 200 sq ft | 40-102 kWh | 85 kWh | 74 |
| 201-400 sq ft | 131-197 kWh | 151 kWh | 86 |
| 401-700 sq ft | 259-344 kWh | 298 kWh | 72 |
| Over 700 sq ft | 335-463 kWh | 388 kWh | 9 |
Across all 241 certified models the median is 152 kWh a year - about $28. The spread by room size is four and a half times, which is why a single "air purifier" figure is not much use: the size you need is set by your room, and the cost follows it almost directly.
Running it around the clock
The label will not tell you this, so here is the arithmetic. A median unit's 152 kWh over 5,840 hours works out to an average draw of about 26 watts. Applied to a full 8,760 hours that is roughly 228 kWh a year, about $42.
Treat that as an approximation rather than a measurement. The certified figure blends active hours with standby hours, and the split between the two is not published per model, so the extra eight hours are charged here at the blended rate rather than at the true active rate. The direction is right and the magnitude is close; the second decimal is not available to anyone.
The agency compares two numbers built on different days
This is worth knowing before you read the saving quoted everywhere.
ENERGY STAR's own page says a standard room air cleaner operating continuously uses approximately 394 kWh a year, and that certified models save consumers about 211 kWh a year - "more than 50% more energy-efficient".
But the certified figures it publishes assume sixteen hours a day, not twenty-four. Part of the advertised gap is a shorter assumed running time rather than a better machine.
The certified models are genuinely more efficient - a median 26 watts against the 45 watts implied by 394 kWh around the clock. The efficiency is real. It is the size of the published saving that carries an assumption inside it, and the assumption is not in the sentence.
"More than some new refrigerators" is true, and understated
The same page adds that 394 kWh a year is "more than the energy used by some new refrigerators!"
We can check that, because refrigerators are certified by the same programme and the data is public. Of 4,788 certified refrigerators, 2,917 use less than 394 kWh a year - that is 61% of them. The median certified refrigerator uses 345 kWh.
So "some" is doing a lot of work in that sentence. A standard air cleaner left running continuously uses more electricity than most new refrigerators on the market, not some.
Per month
152 kWh over twelve months is about 13 kWh a month, roughly $2.30 - on sixteen hours a day. Run continuously, nearer 19 kWh and $3.50. This is one of the cheaper things in the house to leave on; the reason to size it correctly is the room, not the bill.
What it costs you specifically
Set your own tariff below.
What this does not account for
Sixteen hours a day is the assumption, and it is not yours. The certified annual figure assumes 16 hours of active operation daily. If you run the unit continuously the figure is roughly a third higher; if you run it only while you sleep, considerably lower.
Speed setting changes everything and is not in the figure. These machines draw several times more on their highest fan speed than on their lowest, and the certified test uses a defined setting. A purifier on turbo in a smoky room is not the appliance this number describes.
Certified models are a biased sample. Certification is voluntary and efficient models earn it. The agency's own figure for a standard room air cleaner - 394 kWh a year running continuously - is the better reference point for an uncertified machine.
Room size here is the manufacturer's rating. It comes from the clean air delivery rate under a standard test, not from a measurement of your room, and manufacturers rate generously. A unit sized for exactly your floor area will be working harder than one rated above it.
Filters are not in this figure at all. The running cost of an air purifier is usually dominated by replacement filters rather than electricity, and no labelling programme publishes those.
Worth reading next
Sources
- 01ENERGY STAR certified room air cleaners — annual energy use at 16 hours a dayU.S. Environmental Protection Agency ·
- 02Electric Power Monthly, Table 5.3 — average price of electricity to ultimate customersU.S. Energy Information Administration ·
How these figures are produced: see our methodology.
Figures are calculated from published wattages and a published tariff, both dated above. They are good for comparing devices, not for predicting your bill: your rate, settings and usage all differ.