Companion Tool. Air Purifier Buyer's Guide

What CADR does your room actually need?

Most "best air purifier" lists ignore your room. This sizes the exact airflow your space requires (and the real 5-year cost) so you don't overpay or buy a unit that's just decoration.

Required CADR (smoke-rated)

–CFM

Enter your room to size it.

5-Year Cost of Ownership

–

Add a unit's price, filter & watts (optional).

Your room needs a specific number. Anything less is decoration.

Your room

Measure the room the purifier will live in, not the whole floor.

Length (ft)

Width (ft)

Ceiling height (ft)

Primary concern

Air changes per hour (ACH) (how many times the room's full air volume is cleaned per hour)

Noise sensitivity

Why ACH matters, and how to read the CADR number

ACH is how many times per hour the cleaner processes a volume of air equal to your whole room. 4 ACH suits allergies and dust; 5–6+ is the standard for wildfire smoke because fine particles need faster, repeated passes. The required CADR below is the smoke-rated airflow (in CFM) you need to hit that ACH in your room.

Cost a specific unit (optional)

Paste the numbers from a product you're considering to see its true 5-year cost, and whether it's the right size.

Unit price ($)

Unit's rated CADR (CFM)

Replacement filter ($ each)

Filters per year (#)

Power draw (watts)

Run time (hrs/day)

See which models hit this →

Keep reading

Air Purifiers Without the Marketing The full guide behind this tool. Real CADR, noise in decibels, and the five-year filter cost that decides which unit actually fits your room.
Before You Call an HVAC Company If the real problem is weak airflow or uneven temperature, that’s a heating-and-cooling issue, not an air-purifier one. This free tool helps you tell which.

Get the room-sizing cheat sheet

One short email: the CADR ranges for common room sizes, plus the spec lines manufacturers bury. No spam.

Estimates for sizing and cost only, not medical advice; not a guarantee of air-quality outcomes. CADR is a sizing benchmark (AHAM smoke rating); real-world results vary with sealing, doors, and filter condition. Electricity priced at $0.16/kWh (U.S. average estimate): adjust for your own rate.