Air Purifier Buying Guide: What Actually Matters Before You Buy

HEPA, CADR, room size, filter costs, noise... air purifiers come with a lot of confusing specifications. Here's what actually matters.

The 5 Things to Check Before Buying

1. CADR Comes First

CADR (Clean Air Delivery Rate) tells you how quickly a purifier can deliver filtered air.

Don't choose a purifier only because it says "covers 500 sq ft." Compare its CADR with the size of the room you're actually trying to clean.

Our rule: bigger room = higher CADR.

2. HEPA Is Important, But It Isn't Everything

HEPA filters are designed to capture very small airborne particles. But filtration is only useful if enough air actually passes through the filter.

Look at: Filter quality + CADR + airflow rather than obsessing over labels like H13 vs H14.

If odours and gases matter to you, also look for activated carbon.

3. Check the Filter Replacement Cost

This is one of the biggest hidden costs.

A ₹10,000 purifier with a ₹4,000 replacement filter can ultimately cost more than a ₹15,000 purifier with a ₹2,000 filter.

Before buying, check:

• Filter price
• Recommended replacement interval
• Availability of replacement filters

Think beyond purchase price. Think 3-year ownership cost.

4. Noise Matters

A purifier is useless if you stop running it because it's too loud. This is especially important for bedrooms.

Don't only look at the lowest advertised dB level. Check how loud the purifier is at the fan speed you'll actually use.

5. Don't Pay Extra for Features You Won't Use

PM2.5 displays, apps, auto modes and smart-home integration can be useful. But they don't automatically mean better air purification.

Prioritise: CADR → filtration → room size → noise → running cost

Then consider the extras.

What About PM2.5?

If you're buying an air purifier primarily because of pollution, PM2.5 is one of the key pollutants to care about. Look for strong particle filtration and sufficient CADR for your room.

For Indian cities with high outdoor pollution, the purifier's ability to continuously clean fine particles is generally more important than having a long list of smart features.

What About Ionizers and Ozone?

Be cautious about air-cleaning technologies that can generate ozone. More technology doesn't necessarily mean better air. For a home purifier, we'd prioritise proven particle filtration and clear information about ozone emissions.

Our Air Purifier Checklist

Before you buy, ask:

• ✓ Is the CADR appropriate for my room?
• ✓ What filtration system does it use?
• ✓ Does it have activated carbon?
• ✓ How much does the replacement filter cost?
• ✓ How often will I need to replace it?
• ✓ How noisy is it?
• ✓ What will it cost to run?
• ✓ What are actual owners complaining about?

The Product Scanner Approach

We don't believe there's one "best air purifier." The right one depends on what you need.

• 🏆 Best Overall — Best balance of performance, price and ownership cost.
• 🛏️ Best for Bedrooms — Quiet, efficient and suitable for overnight use.
• 💰 Best Value — Strong performance without unnecessary features.
• 🏠 Best for Large Rooms — Higher CADR and sufficient airflow.
• ⚡ Lowest Running Cost — Affordable filters and efficient operation.

Bottom Line

Don't buy an air purifier just because it says "H13 HEPA" or "covers 500 sq ft."

Start with your room size, then compare CADR, filtration, noise and filter costs.

And before you buy, find out what actual owners say.

That's what Product Scanner does. We scan the internet before you buy.