Most Energy-Efficient Air Purifiers (CADR per Watt)

Twin-filter unit with very high claimed CADR; not AHAM listed.

Large-room CADR from a light, efficient unit; short filter life raises running cost.

Efficient medium-room unit; superseded by the 311i Max.

Quieter and more efficient than the 211+, with app control.

Levoit's flagship with a laser sensor and directional vent; expensive for the CADR.

Medium-room Blueair with very low power draw and app.

Very efficient CADR per watt; filters are rated for only six months.

Steel-cabinet workhorse with published test data; no sensor, no app.

Tiny bedroom unit with auto mode and app; fine for a small room, not a living room.

Strong CADR per dollar with app and auto mode; very quiet on low.

Adds a washable prefilter and a pet-hair mode to the Core 400S formula.

Quiet at full speed and well built; price per CADR is high.

High CADR, simple one-button operation, fabric prefilter; no auto mode and short filter life.

211+ with a particle sensor and auto mode.

Compact with a washable prefilter and auto mode.

Premium build and very quiet low speed; CADR per dollar is poor.

High CADR at a quiet 52 dB maximum; annual filter cost is among the highest here.

Airmega 400 with Wi-Fi app control.

Two-sided filtration with a real carbon layer; filters cost more than most.

Large-room Winix with app control and a heavy carbon filter at a mid-range price.

Medium Alen with the same quiet motor; lifetime warranty with filter subscription.

High claimed CADR for the money; not AHAM listed, and filters are short-lived.

45i without the sensor or app.

Sensor-heavy smart unit with swappable filter types; filters are expensive.

Large-room Winix with heavy carbon and app; slightly costlier than the T810.