The short answer
For a typical 150 to 250 sq ft dorm room, a compact true HEPA purifier rated for that size, under about 30 dB on low, with an easy-to-buy replacement filter. Check housing rules for appliances.
What to look for
- A true HEPA stage and a room rating at or above the room's area.
- Low-setting noise under about 30 dB for sleep.
- A small footprint; many fit on a desk or shelf.
- A replacement filter you can afford each semester.
Rules
Most residence halls allow small air purifiers but ban ozone generators and some ionizers. Check the housing appliance list before buying.
Products mentioned
Questions readers ask
Do dorm rooms need an air purifier?
Not necessarily, but they help with allergies, dust and a roommate's habits.
Are ionizers allowed in dorms?
Rules vary; ozone generators are commonly banned, and HEPA purifiers are the safer choice.