What an air purifier costs to run

This is the half of the cost of ownership that nobody puts on a product page, and it is genuinely decision-changing: over five years the running cost can exceed the purchase price and reverse which machine was cheaper.

Two inputs, both somebody else’s, and one multiplication, which is ours.

Input one: certified annual energy use in kWh per year, from AHAM’s directory or the ENERGY STAR database. Produced under ANSI/AHAM AC-1 test conditions, with a duty-cycle assumption already inside it — which is why it is more reliable than multiplying a nameplate wattage by your own guess at hours per day.

Input two: 18.34 cents per kWh, the U.S. average residential price for June 2026 from the EIA’s Electric Power Monthly, Table 5.3.

The sum: annual cost = kWh per year × rate ÷ 100. For the Honeywell HPA4300: 185 × 18.34 ÷ 100 = $34.

Electricity costs on this page use 18.34¢ per kWh, the U.S. average residential price for June 2026 from the U.S. Energy Information Administration, Electric Power Monthly, Table 5.3. Your rate is on your bill and is probably not this one; multiply the kWh figure by your own rate and you have your number.

Look at the Blueair 211i Max and the Whirlpool WPPRO2000. The Blueair delivers more certified air (435 against 341 smoke CADR), across a larger certified room (674 against 529 square feet), for 39% of the electricity.

Or, closer to home for most buyers: the Winix 5500-2 and the Winix AT41 are from the same manufacturer and within 11% on output. The 5500-2 uses 31% more electricity a year. Nothing on either box tells you that.

Quick picks

Ranked on certified Clean Air Delivery Rate against the room size each unit is certified for, then on what it costs to run. Tap any row for the full write-up.

#	Product	Best for	Certified CADR	Price
1	No photo Cheapest to run Honeywell InSight HPA4100 95 kWh a year — under $18 of electricity annually.	Bedrooms up to about 170 sq ft	109CFM smoke AHAM VERIFIDE	Check price on Amazon→
2	No photo Cheapest per unit of air Honeywell InSight HPA4300 7.4 CFM per watt at living-room capability.	True HEPA on the lowest power draw	229CFM smoke AHAM VERIFIDE	Check price on Amazon→
3	No photo Best large-room efficiency Blueair Blue Pure 211i Max 674 certified sq ft on 256 kWh a year — 9.0 CFM per watt.	Open-plan spaces above 500 sq ft	435CFM smoke AHAM VERIFIDE	Check price on Amazon→
4	Most expensive to run Whirlpool Whispure WPPRO2000 657 kWh a year for less air than the Blueair.	Skip this one on running cost	341CFM smoke AHAM VERIFIDE	Check price on Amazon→

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Filters are the rest, and they are far less well documented — most manufacturers publish an interval or a price but not both. What we could and could not source on filter cost.