What size air purifier do I need? Room-size guide with CADR
By the BYM Electronics team · Updated 28 September 2026
Step 1: measure your room
Multiply length by width in feet. A 12 × 14 ft bedroom is 168 sq ft; a 15 × 20 ft living room is 300 sq ft. If the room opens into another space without a door, add both areas.
Step 2: understand CADR
CADR (Clean Air Delivery Rate) is how much filtered air a purifier delivers, usually quoted in m³/h in India. A widely used guideline from AHAM, the US appliance association, is that CADR in cubic feet per minute should be at least two-thirds of the room's floor area in sq ft, for a standard 8 ft ceiling. In m³/h, that works out to roughly 1.1 × your room area in sq ft. For example, a 300 sq ft room needs about 340 m³/h by this rule.
Brands often rate their purifiers for larger rooms than this rule suggests, because they assume fewer air changes per hour. Both numbers are useful: the brand rating tells you the most a purifier can handle, the CADR rule tells you what will clean the air quickly.
Step 3: think about your conditions
- Heavy pollution (winter smog, construction nearby, main road): size up.
- Sleeping: check the sleep-mode noise level; many models run at 13–25 dB in sleep mode.
- Allergies or pets: look for a true HEPA filter and a good pre-filter.
- Running costs: check the replacement filter price and lifespan (see our filter guide).
Every air purifier we sell, by room size
Small rooms and cabins (up to 250 sq ft)
| Model | Rated room size | CADR | Price |
|---|---|---|---|
| Wozoyo Pure Air PA1 Air Purifier | up to 202 sq ft | 110 m³/h | ₹4,799 |
| Honeywell Air Touch V1 Air Purifier | up to 235 sq ft | 152 m³/h | ₹4,799 |
Bedrooms (250–400 sq ft)
| Model | Rated room size | CADR | Price |
|---|---|---|---|
| Carrier Air One AP2006 Air Purifier with UV | up to 300 sq ft | – | ₹10,199 |
| Philips PureProtect Mini 900 Series Air Purifier AC0920/60 | up to 320 sq ft | 250 m³/h | ₹7,699 |
| Philips PureProtect Mini 900 Series Smart Air Purifier AC0950/60 | up to 320 sq ft | 250 m³/h | ₹9,599 |
| Wozoyo Pure Air PA2 Air Purifier | up to 336 sq ft | 165 m³/h | ₹5,799 |
| Philips 1000 Series Air Purifier AC1711/63 | up to 385 sq ft | 300 m³/h | ₹12,299 |
| Philips 1000 Series Smart Air Purifier AC1715/60 | up to 385 sq ft | 300 m³/h | ₹14,499 |
| Honeywell Air Touch V2 Air Purifier | up to 388 sq ft | 250 m³/h | ₹8,799 |
Large bedrooms and living rooms (400–650 sq ft)
| Model | Rated room size | CADR | Price |
|---|---|---|---|
| Honeywell Air Touch V3 Air Purifier | up to 465 sq ft | 300 m³/h | ₹10,099 |
| Philips 2000i Series Smart Air Purifier AC2959/63 | up to 484 sq ft | 380 m³/h | ₹23,199 |
| Philips PureProtect Quiet 2200 Series Smart Air Purifier AC2220 (White) | up to 540 sq ft | 420 m³/h | ₹18,399 |
| Philips PureProtect Quiet 2200 Series Smart Air Purifier AC2221 (Charcoal Grey) | up to 540 sq ft | 420 m³/h | ₹18,399 |
| Honeywell Air Touch V4 Air Purifier with Remote | up to 543 sq ft | 350 m³/h | ₹12,599 |
| Sharp DW-J20FM-W Air Purifier + Dehumidifier | up to 550 sq ft | 258 m³/h (high), 70 m³/h (low) | ₹36,799 |
| Honeywell Air Touch V5 Smart Air Purifier | up to 589 sq ft | Up to 380 m³/h | ₹9,399 |
| Philips PureProtect 3200 Series Smart Air Purifier AC3221/63 | up to 600 sq ft | 520 m³/h | ₹19,799 |
| Wozoyo Pure Air PA4 2-in-1 Air Purifier + Fan | up to 605 sq ft | 270 m³/h | ₹11,099 |
Large living rooms, halls and offices (650 sq ft and above)
| Model | Rated room size | CADR | Price |
|---|---|---|---|
| Philips PureProtect 3200 Series Smart Air Purifier AC3220/60 | up to 670 sq ft | 520 m³/h | ₹18,899 |
| Honeywell Air Touch P1 Air Purifier | up to 698 sq ft | 450 m³/h | ₹14,499 |
| Philips PureProtect Pro 4200 Series Smart Air Purifier AC4221/61 | up to 775 sq ft | 600 m³/h | ₹23,599 |
| Wozoyo Pure Air PA5 Air Purifier | up to 785 sq ft | 450 m³/h | ₹12,999 |
| Honeywell Air Touch U2 Smart Air Purifier with Humidifier | up to 1008 sq ft | 650 m³/h | ₹27,099 |
| Wozoyo Pure Air PA6 Air Purifier | up to 1458 sq ft | 700 m³/h | ₹25,599 |
Room sizes and CADR are as quoted by each brand. Prices include GST and may change.
Still unsure? WhatsApp us your room size and we'll suggest two or three options.
Frequently asked questions
What size air purifier do I need for a 150 sq ft room?
A purifier rated for at least 150–250 sq ft, with a CADR of about 170 m³/h or more.
What size air purifier do I need for a 300 sq ft room?
One rated for 300 sq ft or more, ideally with a CADR of 340 m³/h or higher for fast cleaning.
Is a bigger air purifier always better?
A higher-capacity purifier cleans a room faster and can run on a quieter setting, but it costs more and its filters are usually pricier. Match it to your room, then size up for heavy pollution.
Can one air purifier clean the whole house?
No. Purifiers work best in one closed room. Use one per room you spend the most time in, usually the bedroom first.