How to use this case study
This post walks through the Xiaomi Air Purifier 4 and Air Purifier 4 Lite using our 8-step Buying Checklist. Every row below maps directly to the interactive Buying Checklist toolso you can follow along and fill in your own evaluation as you read.
Sources: Xiaomi India official specs and GB/T 18801-2015 standard. You can also compare with our Dyson HJ10 case study or the Honeywell Air Touch walkthrough.
Disclaimer: This is an independent case study for educational purposes only, not a promotion or endorsement of Xiaomi products. We have no affiliation with Xiaomi or any air purifier brand.
Quick specs at a glance
| Spec | AP4 | AP4 Lite |
|---|---|---|
| CADR | 400 m³/h | 360 m³/h |
| Filter type | High-Efficiency Filter | High-Efficiency Filter |
| Carbon | 500,000 mg | 450,000 mg |
| Noise (sleep) | 32.1 dB(A) | 33.4 dB(A) |
| Power (max) | ~33 W | ~33 W |
| Ioniser | Yes, can disable via app | No |
Not sure what CADR you need for your room? Use our Air Purifier CADR Calculator to find the right size in under a minute.
1. Room Sizing
| Checklist Item | AP4 | AP4 Lite | Notes |
|---|---|---|---|
| Room volume calculated | Yes | Yes | Prerequisite step: measure your room before comparing CADR figures. |
| CADR matches required ACH (5 air changes/hr) | Yes | Yes | AP4 covers ~28 m² (301 sq.ft.) at the lower end; AP4 Lite covers ~25 m² (269 sq.ft.). For Delhi-level AQI 200+, size against lower-end figures. |
| Purifier slightly oversized (~20–30%) | Needs attention | Needs attention | After a 25% real-world buffer, effective coverage drops to ~236 sq.ft. (AP4) and ~212 sq.ft. (AP4 Lite) at 9 ft ceiling. Best suited for rooms up to ~210–235 sq.ft. (AP4) and ~190–210 sq.ft. (AP4 Lite). |
Coverage area deep-dive
GB/T 18801 tests are conducted in a sealed, unfurnished ~30 m³ chamber. Real homes have furniture, gaps under doors, and people moving, all of which reduce effective CADR. For Delhi/NCR where AQI regularly exceeds 200, always size against the lower end and apply a 20–30% buffer.
| Parameter | AP4 | AP4 Lite |
|---|---|---|
| Particle CADR (manufacturer rated) | 400 m³/h | 360 m³/h |
| Effective area, lower end (high pollution) | 301 sq.ft. (~28 m²) | 269 sq.ft. (~25 m²) |
| Effective area, upper end (light pollution) | 516 sq.ft. (~48 m²) | 463 sq.ft. (~43 m²) |
| CADR after 25% real-world buffer | 300 m³/h | 270 m³/h |
| Practical coverage at 5 ACH (9 ft ceiling) | ~21–22 m² (~236 sq.ft.) | ~19–20 m² (~212 sq.ft.) |
| Practical coverage at 5 ACH (10 ft ceiling) | ~19–20 m² (~212 sq.ft.) | ~17–18 m² (~190 sq.ft.) |
| Verdict for large rooms (>30 m²) | Borderline, consider larger unit | Insufficient, upgrade recommended |
2. Filters
| Checklist Item | AP4 | AP4 Lite | Notes |
|---|---|---|---|
| True HEPA (H13/H14 preferred) | Needs attention | Needs attention | Uses 'High-Efficiency Filter' branding, officially rated at 99.99% at 0.1 μm. Not standard HEPA-graded (H13/H14), but proprietary filter technology. |
| Activated carbon filter | Yes | Yes | AP4: 500,000 mg activated carbon. AP4 Lite: 450,000 mg activated carbon. |
| Washable pre-filter | No | No | Pre-filter is integrated into the all-in-one cartridge, not separately washable on either model. |
| Filter replacement cost checked | Yes | Yes | AP4 Lite filter ~₹2,980 (mi.com India). AP4 filter similar. Interval: 6–12 months. |
| Adequate carbon thickness | Yes | Yes | AP4: 500,000 mg. AP4 Lite: 450,000 mg. Both use activated carbon for VOC/odour removal. Carbon form type not specified on official pages. |
3. Sensors & Modes
| Checklist Item | AP4 | AP4 Lite | Notes |
|---|---|---|---|
| Real-time PM2.5 display | Yes | Yes | AP4: OLED touch display with PM2.5 + colour indicator. AP4 Lite: LED display with PM2.5 + colour strip. |
| TVOC sensor | No | No | Neither model lists a dedicated TVOC sensor in official specs. |
| Night / Sleep mode | Yes | Yes | AP4: 32.1 dB(A). AP4 Lite: 33.4 dB(A), both under 35 dB bedroom threshold. |
| Auto mode | Yes | Yes | Both auto-adjust fan speed based on real-time PM2.5 sensor readings. |
4. Performance
| Checklist Item | AP4 | AP4 Lite | Notes |
|---|---|---|---|
| Verified CADR (AHAM or trusted tests) | Needs attention | Needs attention | Tested by China Testing & Inspection Institute (GB/T 18801-2015), not AHAM-certified. |
| Noise level acceptable | Yes | Yes | Night mode: AP4 = 32.1 dB(A), AP4 Lite = 33.4 dB(A), both suitable for bedrooms. |
| Power consumption reasonable | Yes | Yes | Both rated ~33 W max. ~0.8 kWh per 24 hours, very efficient for 24×7 use. |
5. Usability
| Checklist Item | AP4 | AP4 Lite | Notes |
|---|---|---|---|
| Filter change indicator | Yes | Yes | Both show filter life status in the app with replacement reminders. |
| App / Wi-Fi | Yes | Yes | Both support app control, Alexa & Google Assistant. Basic on-device controls available without app. |
| Replacement filters available in India | Yes | Yes | Available on mi.com India and major e-commerce platforms. Some stock variability reported for AP4 Lite filter. |
6. Cost & Service
| Checklist Item | AP4 | AP4 Lite | Notes |
|---|---|---|---|
| 3-year total cost calculated | Yes | Yes | AP4 Lite ~₹15,999 + ~₹3,000/yr filters + ~₹1,000/yr electricity ≈ ₹27,000 over 3 yrs. AP4 slightly higher, both reasonable for the category. |
| Warranty of 1–2+ years | Needs attention | Needs attention | Both carry only 1-year warranty (consumable filters excluded). |
| Service network available | Needs attention | Needs attention | Check with the company for local service centre availability and post-warranty repair support before purchase. |
7. Things to Avoid
| Checklist Item | AP4 | AP4 Lite | Notes |
|---|---|---|---|
| Negative ioniser present? | Needs attention | Yes | AP4: officially lists a negative ioniser, TÜV Rheinland Allergy Care certified, but any ozone output is a concern for sensitive lungs. Can be disabled via the app. AP4 Lite: ioniser not mentioned in spec sheet. |
| UV-C as primary cleaning method? | Yes | Yes | Neither model uses UV-C, good. |
| "HEPA-type" or "HEPA-like" labelling? | Needs attention | Needs attention | Uses proprietary "High-Efficiency Filter" branding, officially rated at 99.99% at 0.1 μm, but not standard HEPA-graded. |
| Relying on indoor plants / VOC-only claims? | Yes | Yes | Neither model makes such claims, good. |
Who should buy which?
Choose AP4 if…
- Your room is 22–28 m² (at 9–10 ft ceiling, high pollution sizing)
- You need higher carbon capacity (500,000 mg vs 450,000 mg)
- You want the OLED touch display
- You're OK disabling the ioniser via the app
Choose AP4 Lite if…
- Your room is 18–25 m² (at 9–10 ft ceiling, high pollution sizing)
- You want to avoid the ioniser entirely
- Budget matters, lower purchase price
- VOC/odour concerns are mild (450,000 mg carbon is adequate for most homes)
References
All sources mi.com/in. Accessed March 2026.
Product pages, mi.com/in
- Mi Air Purifier 4 official product page, Xiaomi India ↗
- Mi Air Purifier 4 Lite official product page, Xiaomi India ↗
Related posts on indoorair.guide
- Air Purifier Buying Checklist for Indian Homes
- HEPA 13 vs HEPA 14: Which Filter Do You Actually Need?
- ACH Calculator
Independent, India-focused IAQ resource. Not affiliated with Xiaomi or any manufacturer. Verify specifications before purchase.
All references collated on the Reference Papers page.
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