Enter your room dimensions and type to get an instant CADR recommendation. Our calculator considers room-specific factors to find the perfect air purifier for your space.
Standard ceiling height - most air purifiers are optimized for this range.
Bedrooms benefit from 10% higher CADR for better sleep quality and allergen control.
Ideal for medium-sized air purifiers. Many popular models are designed for this range.
See how our calculator determines the perfect CADR for different room types and sizes
Needs 120 CFM CADR minimum. Bedroom multiplier ensures quiet, restful sleep while maintaining clean air throughout the night.
Needs 250 CFM CADR minimum. Higher activity levels and foot traffic require stronger purification to maintain air quality.
Needs 75 CFM CADR minimum. Compact units work well for focused productivity while maintaining healthy indoor air quality.
Needs 405 CFM CADR minimum. Kitchen multiplier accounts for cooking odors, grease particles, and higher pollution from meal preparation.
Needs 448 CFM CADR minimum. Basement multiplier addresses humidity, musty odors, and potential mold issues common in below-grade spaces.
Every room is unique. Get precise CADR requirements based on your exact square footage, ceiling height, and room type.
Our Room Size Calculator makes it easy to find the perfect air purifier for your space. Simply enter your room details and get instant CADR recommendations based on square footage, ceiling height, and room-specific factors.
Measure the length and width of your room in feet, then multiply to get square footage. For example: 15 ft × 12 ft = 180 sq ft. Use the slider or type directly for precise input.
Choose your ceiling height from the dropdown. Standard residential ceilings are 8 feet, but newer homes often have 9-10 feet. Higher ceilings mean more air volume to clean.
Select your room type to apply the appropriate CADR multiplier. Different rooms have varying air quality needs:
Get your recommended CADR with a suggested range for flexibility. The calculator also shows air changes per hour, room volume, and efficiency ratings to help you understand the results.
The calculator provides several key metrics to help you choose the right air purifier. Here's what each number means and how to use this information when shopping for your ideal air cleaning solution.
This is your target Clean Air Delivery Rate in CFM (cubic feet per minute). It's calculated based on your room volume, ceiling height, and room type. Look for air purifiers with CADR ratings at or above this number.
Example: For a 300 sq ft bedroom with 8 ft ceilings, you need about 200 CFM CADR. A 250 CFM unit would work perfectly and provide extra capacity.
We provide a range (minimum to maximum) to give you flexibility. Choose the minimum for basic cleaning, middle range for standard use, or maximum for allergies, pets, or heavy pollution.
Flexibility: Higher CADR units can run on lower speeds for quieter operation while maintaining effectiveness.
This shows how many times your room's air gets completely filtered each hour. Higher numbers mean faster, more thorough cleaning:
The relationship between room size and CADR (Clean Air Delivery Rate) is fundamental to effective air purification. Understanding this connection helps you choose the right air purifier size and avoid common sizing mistakes.
CADR needed = (Room Volume ÷ 60) × Target ACH. For example, a 2,400 cubic foot room targeting 5 ACH needs 200 CFM CADR minimum.
Larger rooms contain more air that needs filtering. An undersized air purifier will run constantly at maximum speed, creating noise while struggling to maintain clean air.
Many people buy air purifiers based on "room coverage" claims without considering ceiling height or room type. Marketing square footage can be misleading.
| Room Size | 8 ft Ceiling | 9 ft Ceiling | 10 ft Ceiling | Recommended Units |
|---|---|---|---|---|
| 150 sq ft | 100-150 CFM | 115-170 CFM | 125-190 CFM | Compact desktop units |
| 300 sq ft | 200-300 CFM | 225-340 CFM | 250-375 CFM | Medium room units |
| 500 sq ft | 335-500 CFM | 375-565 CFM | 415-625 CFM | Large room units |
| 750 sq ft | 500-750 CFM | 565-845 CFM | 625-940 CFM | Multiple units or industrial |
See how our room size calculator works with real-world examples. Each scenario shows different considerations and explains why specific CADR ratings are recommended.
Basic CADR: 120 × 0.67 = 80 CFM
Allergy CADR: 120 × 1.0 = 120 CFM
Recommended: 80-120 CFM
✓ Compact desktop unit sufficient
Why this works: Small bedrooms need moderate air cleaning focused on nighttime pollutants. A 100 CFM unit provides 6+ air changes per hour, ideal for allergy relief without excessive noise.
Basic CADR: 300 × 0.67 = 200 CFM
Pet CADR: 300 × 1.25 = 375 CFM
Recommended: 300-375 CFM
✓ Large room unit or 2 medium units
Why this works: Pet dander requires higher air turnover rates. The 375 CFM recommendation provides 5+ air changes per hour, effectively capturing dander and controlling odors from litter boxes.
Basic CADR: 450 × 0.67 = 300 CFM
Cooking CADR: 450 × 1.5 = 675 CFM
Recommended: 500-675 CFM
✓ Multiple units strategy recommended
Why this works: Open floor plans and cooking areas need higher capacity. Consider placing one 350 CFM unit near the kitchen and another 300 CFM unit in the living area for optimal coverage and air circulation.
Basic CADR: 168 × 0.67 = 112 CFM
Premium CADR: 168 × 1.0 = 168 CFM
Recommended: 110-170 CFM
✓ Medium desktop unit with quiet operation
Why this works: Home offices need consistent air quality without noise distraction. A 150 CFM unit provides 6.7 air changes per hour while maintaining whisper-quiet operation on medium settings.
Basic CADR: 288 × 0.67 = 193 CFM
Premium CADR: 288 × 1.25 = 360 CFM
Recommended: 250-360 CFM
✓ Large bedroom unit with smart features
Why this works: Large bedrooms benefit from higher-capacity units that can operate on low speeds. A 300 CFM unit provides excellent air quality while running virtually silent during sleep hours.
Bedrooms need quieter operation, kitchens need higher capacity for particles, and offices need consistent air quality.
Higher ceilings significantly increase room volume, requiring proportionally higher CADR ratings for effective air cleaning.
Pets, cooking, allergies, and open floor plans all require sizing up your air purifier for optimal performance.
Get answers to the most common questions about room size calculations, CADR requirements, and air purifier selection.
For irregular rooms, calculate the total floor area by breaking it into rectangles and adding them together. The calculator uses total square footage, so shape doesn't directly affect the CADR recommendation.
L-shaped rooms: Measure each section separately (e.g., 12'×15' living area + 8'×10' dining nook = 180 + 80 = 260 sq ft total).
Rooms with alcoves: Include all floor space where air needs to be cleaned. Consider placing the air purifier centrally for better circulation in irregular spaces.
Choose based on your specific air quality needs and tolerance for noise:
Pro tip: When in doubt, choose higher CADR. You can always run a powerful unit on lower speeds for quieter operation.
Absolutely! Higher CADR is generally better and offers several advantages:
The only downsides are higher upfront cost and potentially higher energy consumption if run at full speed constantly.
Open floor plans require special consideration because air moves freely between spaces:
Example: A 600 sq ft open floor plan might benefit from two 300 CFM units rather than one 600 CFM unit for better air circulation.
Different rooms have varying pollution sources, occupancy patterns, and air quality requirements:
High-Pollution Rooms:
Sensitive Rooms:
Match your CADR to both room size and pollution level for optimal air quality.
Room measurements should be reasonably accurate, but perfect precision isn't critical:
Pro tip: When measurements are borderline between size categories, choose the higher CADR for better performance.
Special circumstances require higher CADR ratings for effective air cleaning:
Size Up For:
Filter Considerations:
Remember: our calculator provides baseline recommendations. Add 25-50% CADR for challenging environments.
The answer depends on your room size, layout, and budget:
Multiple Smaller Units:
One Large Unit:
Best practice: For large rooms (500+ sq ft), consider two units with 60-70% of the total required CADR each.
Ceiling height directly affects room volume and air circulation patterns:
Volume Impact Examples:
Practical implications:
Our calculator automatically adjusts for ceiling height, but rooms over 10 feet may benefit from additional circulation assistance.
CADR ratings test three different particle sizes that represent common indoor pollutants:
Dust (0.5-3 μm)
Pollen (5-11 μm)
Smoke (0.09-1 μm)
For room sizing: Use the dust CADR rating as it typically represents the unit's overall performance for most household pollutants. If you have specific concerns about smoke or fine particles, prioritize the smoke CADR rating.
Jump directly to specialized calculators for common room sizes. Each includes detailed guides, product recommendations, and room-specific optimization tips.