Room by Room · reference
Air Purifier for a Bedroom: What Size You Need
for a typical bedroom
EPA table, 200 sq ft row · 8-ft ceiling
Sizing an air purifier for a bedroom is arithmetic before it is shopping. Measure the floor area, take the published minimum CADR for that area, and treat the coverage figure on the box as decoration. EPA publishes the numbers that count.
What makes a bedroom different is that you sleep in it. The machine runs within reach all night, so noise decides whether it stays. An oversized unit on its low setting is quieter than an undersized one on high, which turns the usual 'buy small' instinct upside down. And an open door quietly changes the room you just sized.
What the published table gives a bedroom#
A typical bedroom sits between the 100 and 200 sq ft published rows, so the minimum that governs it is 130 cfm. When a floor area falls between two rows, take the larger, CADR is a minimum, and minimums do not reward optimism.
The rows assume an 8-foot ceiling. Most bedrooms have one. If yours is taller, EPA says you may want a unit with a higher CADR.
| Room area | Minimum CADR |
|---|---|
| 100 sq ft | 65 cfm |
| 200 sq ft | 130 cfm |
| 300 sq ft | 195 cfm |
| 400 sq ft | 260 cfm |
| 500 sq ft | 325 cfm |
| 600 sq ft | 390 cfm |
The loudest setting is the wrong target#
The published minimum says how much clean air a machine must deliver. It says nothing about how loud it is while delivering it. Two units with the same CADR can sound nothing alike on their low settings.
An undersized unit has to run on high all night to reach the minimum. An oversized one can sit on low and still clear it. If sleep is the point, the bigger machine is often the quieter one. Compare a few models sized for a bedroom before deciding, and judge them on the low setting.
Suggested next step
Compare what the table asks for
Search listings for the published minimum your room needs, then check the smoke CADR on the shortlist before anything else.
Placement and running#
And check the pre-filter when you can see dust on it. In a bedroom that is a glance, not a chore.
- Leave clearance on every side so air can actually pass through the machine.
- Keep it out of the curtain line; fabric blocks airflow and gathers dust.
- Run it from before you sleep until after you wake. Particles return when it stops.
- A closed door keeps the room you sized. An open door quietly adds the landing to it.
The two things the box will not tell you#
First: if the box promises to remove smells, there is no published CADR behind that claim. EPA's rating covers particles, smoke, dust and pollen. Odours are gases, and no minimum exists for them at any room size.
Second: if the box leads with a MERV rating, that is a furnace-filter rating. It describes how well a filter captures particles, not how large a room a machine serves. EPA publishes no MERV-by-room-area table.
Questions people actually ask
Sources
- U.S. Environmental Protection Agency, Guide to Air Cleaners in the Home (2nd edition), retrieved 2026-08-30
Quoted and transcribed, never paraphrased into new numbers. This site does not interpolate between published figures.
Suggested next step
One more angle before you decide
The minimum is settled, spend the rest of the decision on noise, filter cost and the smoke CADR.
Get the next sizing brief
One email when a page earns its figure. No deal alerts, this site does not show prices.
Printed from https://roomandfilter.com/rooms/air-purifier-for-a-bedroom, “Air Purifier for a Bedroom: What Size You Need”. Figures from U.S. Environmental Protection Agency, Guide to Air Cleaners in the Home (2nd edition), retrieved 2026-08-30. No prices are shown on this site, by policy.