Best Air Purifier Under $100 (October 2026)

CADR, and how to size one properly

CADR - Clean Air Delivery Rate - is the single useful specification in this category. It measures how much filtered air the unit actually delivers, in cubic feet per minute, and it is verified independently by AHAM for units that carry the certification.

The practical rule: your CADR should be roughly two-thirds of your room's square footage for a decent air change rate. A 200 square foot bedroom wants a CADR around 130; a 400 square foot living room wants around 260.

Manufacturers advertise a coverage area instead, calculated at a low air-change rate that sounds generous. A unit claiming 400 square feet often has a CADR suited to 200. Look for the CADR number and do the arithmetic yourself.

Also: an undersized purifier running constantly beats an oversized one you turn off because it is loud. Noise is the main reason purifiers get switched off, so check the decibel figure on the lowest setting - that is the one it will actually run at overnight.

The filter cost is the real price

This is the thing roundups skip because the commission is on the hardware. Work it out before you buy.

A $90 purifier with $30-a-year filters costs $180 over three years. A $60 purifier with proprietary $55 filters replaced twice a year costs $390 over the same period. The cheaper purifier is more than twice as expensive.

Two things to check: the price of a genuine replacement filter, and how often the manufacturer says to change it - typically every six to twelve months depending on use.

Third-party filters exist for popular models and are considerably cheaper, with the usual caveat that quality varies. For a widely-sold unit like the Levoit Core 300, that market is mature; for an obscure brand it may not exist at all, which is a reason to prefer a popular model.

• Match CADR to about two-thirds of your room's square footage.
• Check the filter price and replacement interval before the purifier price.
• Check the noise level on the lowest setting - that is the one you will use.

What an air purifier can and cannot do

It can reduce airborne particulates: dust, pollen, pet dander, smoke particles and some mold spores. HEPA filtration at H13 grade captures the overwhelming majority of particles in the relevant size range, and that is a genuine, measurable effect.

It cannot fix damp or mold at the source - that is a ventilation and moisture problem, and a purifier addresses the symptom while the cause continues. A dehumidifier is the right tool there.

It cannot remove gases without a substantial activated carbon stage, and the thin carbon mesh in most budget units does very little for VOCs.

Ionisers and UV stages are marketing more often than function on budget units. Some ionisers produce small amounts of ozone, which is an irritant. If a unit has one, our view is to leave it switched off.

Our full guide to cheap air purifiers goes through the evidence in more detail.

When to spend more

A larger room is the main reason. Open-plan living spaces need a CADR that simply is not available under $100, and running an undersized unit in a large room produces very little benefit.

A genuinely substantial carbon stage for smoke or chemical odors is the second - that means pounds of carbon rather than a coated mesh, and it costs real money.

For a bedroom or a home office, the units on this page do the job properly and spending more buys coverage you do not need.