Air Purifier Room Size Calculator: CADR for Bedrooms

Updated: May 9, 2026.

Air Purifier Buying Basics

Start with the full HealthGlean bedroom air purifier guide, then use this CADR calculator and these explainers to size the purifier, evaluate filter claims, and avoid ozone mistakes.

Use this air purifier room size calculator before buying a small-bedroom purifier. CADR means clean air delivery rate, and it is one of the most useful air-purifier numbers because it combines airflow and particle removal into a practical output: how much filtered air the machine delivers.

Room-size claims can be fuzzy, especially when brands use different air-change assumptions. For bedrooms, CADR is more useful than square footage alone because it helps you choose a purifier that can clean the room without needing to run loudly all night.

Air Purifier Room Size Calculator

Enter the room dimensions, then compare the minimum CADR with a stronger quiet-bedroom or smoke target.

Room length in feet Room width in feet Ceiling height in feet Primary use

Use the calculator to estimate CADR for your room.

Small Bedroom CADR Quick-Reference Chart

Use this quick chart when you want a fast shortlist before using the calculator. The basic minimum follows the AHAM two-thirds room-area rule for an 8 ft ceiling. The quiet-bedroom target adds a buffer so you are less likely to rely on the loudest fan setting overnight. The smoke target uses a more conservative smoke CADR equal to room area.

Room Size	Room Area	Basic Minimum CADR	Quiet-Bedroom Target	Smoke/Wildfire Particle Target
9 ft x 10 ft	90 sq ft	About 60 cfm	About 80 cfm	About 90 smoke CADR
10 ft x 10 ft	100 sq ft	About 65 cfm	About 85 cfm	About 100 smoke CADR
10 ft x 12 ft	120 sq ft	About 80 cfm	About 105 cfm	About 120 smoke CADR
11 ft x 12 ft	132 sq ft	About 90 cfm	About 115 cfm	About 132 smoke CADR
12 ft x 14 ft	168 sq ft	About 112 cfm	About 145 cfm	About 168 smoke CADR

For ceilings higher than 8 ft, multiply the target by ceiling height divided by 8. For example, a 10 ft ceiling needs about 25% more CADR than the same floor area with an 8 ft ceiling.

The Basic Sizing Rule

EPA says the CADR should be large enough for the room, and AHAM gives a simple rule of thumb: the CADR should be at least two-thirds of the room area in square feet. For wildfire smoke, AHAM recommends a smoke CADR equal to the room area.

Bedroom Size	Room Area	Minimum CADR By 2/3 Rule	Stronger Smoke/Wildfire Target
10 ft x 10 ft	100 sq ft	About 65 cfm	About 100 smoke CADR
10 ft x 12 ft	120 sq ft	About 80 cfm	About 120 smoke CADR
12 ft x 14 ft	168 sq ft	About 112 cfm	About 168 smoke CADR
14 ft x 16 ft	224 sq ft	About 149 cfm	About 224 smoke CADR
16 ft x 20 ft	320 sq ft	About 213 cfm	About 320 smoke CADR

Use Smoke CADR For Small Particles

Some labels show separate CADR numbers for smoke, dust, and pollen. EPA explains that tobacco smoke, dust, and pollen represent small, medium, and large particles. For fine particles and bedroom smoke concerns, smoke CADR is usually the most conservative number to compare.

Why Bedroom Sizing Needs A Buffer

CADR is usually measured on high: a purifier that is barely adequate on high may be noisy on the setting you actually use for sleep.
Ceiling height matters: EPA notes that rooms above 8 feet may need a larger purifier.
Open doors change the room: an open bedroom door can make the purifier serve part of a hallway or living space.
Filter age matters: airflow and performance can fall when filters are dirty or overloaded.
Smoke events are different: wildfire smoke or heavy outdoor particle events call for more conservative sizing and public-health guidance.

Practical Formula

Measure length times width. Multiply the room area by 0.67 for a basic minimum CADR. If the ceiling is higher than 8 feet, multiply the result by ceiling height divided by 8. Then consider sizing up if you want quiet overnight operation, have pets, smoke exposure, or an open floor plan.

Air Purifier CADR FAQ

What CADR do I need for a 10 by 12 bedroom?

A 10 by 12 bedroom is 120 sq ft. The basic AHAM two-thirds rule points to about 80 cfm CADR for an 8 ft ceiling. For quieter overnight use, look closer to 100 to 120 cfm so the purifier has room to work below its loudest setting.

Should I compare smoke CADR, dust CADR, or pollen CADR?

For small particles and bedroom concerns, smoke CADR is usually the stricter comparison number. Dust and pollen CADR can still be useful, but smoke CADR is the safer single number when you are trying to avoid undersizing.

Is a higher-CADR purifier too big for a small bedroom?

Not automatically. A higher-CADR purifier can be useful if it runs quietly on lower speeds. The tradeoffs are price, footprint, filter cost, and whether the lowest fan setting is still comfortable at night.

Why do brand room-size claims differ from this calculator?

Brands may use different air-change assumptions, ceiling heights, fan speeds, or one-hour coverage claims. That is why CADR and the fan setting you will actually use are more practical than square footage alone.

Does CADR solve gases, odors, mold, or medical symptoms?

No. CADR is mainly a particle-cleaning metric. It does not rate gases or VOCs, and an air purifier does not replace source control, mold repair, ventilation when outdoor air is clean, or advice from a qualified clinician for respiratory symptoms.

After sizing the room, use the HealthGlean bedroom air purifier guide to compare real product picks by CADR, low-speed noise, filter cost, and ionizer notes.

Sources And References

We checked these references on May 9, 2026. Product CADR, room-size claims, filter schedules, ionizer settings, and certification status can change, so verify the exact model before buying or replacing filters.

Informational note: This article is general education and shopping guidance, not medical advice. Air purifiers can support indoor-air control, but they do not replace source control, ventilation when outdoor air is clean, mold repair, smoke avoidance, or care from a qualified clinician for asthma, allergies, COPD, infection risk, or other respiratory concerns.