Levoit’s Core 400S and Core 600S sit one step apart in the same lineup, run the same VeSync app, and use the same three-stage filter design. The only real question is how much air you need moved per hour — and that answer is set by your room, not by the spec sheet. Here is where the two models genuinely diverge.

Quick Answer

Buy the Core 400S if your room is roughly 350 sq ft or smaller — a standard bedroom, a home office, a mid-size living room — and you want the smaller footprint, lower power draw and quieter top end. Buy the Core 600S if you are covering an open-plan living area, a basement, or anything from about 400 sq ft up to 600 sq ft, or if you want faster clean-up during wildfire smoke and cooking events in a medium room. The 600S is not simply “the better one” — in a small bedroom it is oversized, louder at the top of its range, and you pay for airflow you will never use.

Specs at a Glance

Spec	Levoit Core 400S	Levoit Core 600S
CADR (current -P listing)	231 CFM	391 CFM
CADR (earlier listings)	260 CFM	410 CFM
Coverage at 4.8 ACH	358 sq ft	606 sq ft
Coverage at 1 ACH	1,718 sq ft	2,909 sq ft
Quoted noise range	22–52 dB	26–55 dB
Rated power	38W	49W
Dimensions	10.8 x 10.8 x 20.5 in	12.3 x 12.3 x 23.6 in
Weight	11 lb	13.7 lb
Filtration	3-stage: pre-filter, HEPA, activated carbon	3-stage: pre-filter, HEPA, activated carbon
Replacement filter	Model-specific (not shared)	Model-specific (not shared)
Ionizer	None	None
Smart control	VeSync app, Alexa, Google Assistant	VeSync app, Alexa, Google Assistant
Certifications	Energy Star, CARB	Energy Star, CARB
Warranty	2-year limited	2-year limited

Two notes on that table. First, Levoit revised the published CADR figures when the current -P versions replaced the originals, so you will still see 260 CFM and 410 CFM on plenty of retail listings. Because CADR is a certified figure rather than a brand claim, the current numbers for any given model are also searchable in AHAM’s Directory of Certified Air Cleaners. Both sets of numbers describe the same relationship: the 600S moves roughly 65–70% more air than the 400S. Second, the two coverage rows are not two opinions — they are the same machine measured against different air-change targets. If any of that is unfamiliar, our explainer on what CADR ratings actually mean unpacks it.

Coverage Is the Only Number That Decides This

The 4.8 ACH figure — 358 sq ft for the 400S, 606 sq ft for the 600S — is the one to shop by. It means the unit turns over all the air in that room about every 12.5 minutes on its highest setting. That is the rate you want when something is actively polluting the air: cooking, a litter box, smoke drifting in through the windows, or pollen tracked in on clothes.

The 1 ACH figure (1,718 and 2,909 sq ft respectively) is the marketing number. One air change per hour is enough to keep already-clean air clean, and nowhere near enough to pull down a spike. A 600S in a 2,900 sq ft house is not purifying that house.

So measure the room, then match. Under 350 sq ft, the 400S has headroom and will spend most of its life on low or medium. Between 350 and 600 sq ft, the 600S is the honest choice. Above that, you are into multiple-unit territory, which is the territory covered in our guides to the best air purifiers for large rooms and specifically to 1,000 sq ft spaces.

Noise: The Quieter Model Isn’t Always the Quieter Choice

On paper the 400S wins: 22–52 dB against 26–55 dB. Its floor is lower and its ceiling is lower, which matters if the purifier lives on a nightstand.

But the comparison flips once you fix the room. Say you have a 400 sq ft living room. The 400S has to sit near the top of its fan range to keep up, which puts it close to that 52 dB ceiling for hours at a stretch. The 600S delivers the same volume of clean air at a middling fan speed, well below its 55 dB maximum. Airflow demand, not the spec sheet, sets the noise you actually live with — the same logic behind our advice on where to place an air purifier in a bedroom.

The reverse is also true and worth saying plainly. Put a 600S in a 150 sq ft bedroom and you will run it on sleep mode permanently, where its 26 dB floor is audibly present in a way the 400S’s 22 dB is not. Oversizing is a real cost, not free insurance.

Power, Size and Ongoing Cost

The 400S draws up to 38W, the 600S up to 49W. Both are Energy Star certified — the ENERGY STAR room air cleaner listings are the place to confirm that for a specific model number — and neither will show up meaningfully on a power bill even running around the clock. The gap only matters if you are running several units continuously.

Physically, the 600S is about 1.5 inches wider and 3 inches taller, and roughly 2.7 lb heavier. Neither is heavy, but the 600S is noticeably a piece of furniture where the 400S can tuck beside a desk.

Filters are the part people underestimate. The two models use different, non-interchangeable filter cartridges, so you cannot buy in bulk across both if you own one of each. Both are three-stage units — nylon pre-filter, HEPA layer, activated carbon — sold as a single replaceable cartridge, and Levoit’s guidance is a replacement roughly every 6 to 12 months depending on how hard the unit works. The 600S cartridge is larger and costs more per swap. Vacuuming the outer surface between changes stretches life considerably; our guide to how often to change a HEPA filter covers the signals that a cartridge is genuinely spent.

Worth noting for anyone sensitive to it: neither model has an ionizer, and both are CARB certified — you can check any specific model against CARB’s list of certified air cleaning devices. There is no ozone-generating mode to remember to switch off, which puts them both on the shortlist in our no-ozone air purifier roundup.

Which One for Your Situation

Bedroom or home office, under 250 sq ft. The 400S, and honestly you could go smaller. If this describes you, read our Core 300 vs 400 comparison before spending up — the step down may serve you better and quieter.

Mid-size living room, 250–350 sq ft. The 400S. It has enough margin to sit on medium most of the time, and the smaller cabinet is easier to place.

Open-plan living/kitchen or a converted basement, 400–600 sq ft. The 600S. This is exactly the gap it exists to fill, and the 400S will simply run flat out and lose ground during cooking.

Allergies, pets or smoke in a medium room. Lean 600S even if the square footage says 400S. Higher CADR means faster recovery after a trigger event, and you can run it lower the rest of the time. The same reasoning appears in our wildfire smoke picks and in the pet allergy guide.

FAQ

Is the Levoit Core 600S worth it over the 400S? Only if your room is bigger than roughly 350 sq ft, or if you want faster recovery from smoke and cooking in a mid-size room. In a small bedroom the extra CADR goes unused and you get a slightly louder floor and a pricier filter.

Can I use a Core 400S filter in a Core 600S? No. The cartridges are different sizes and are sold as model-specific parts. Buy the filter that matches your unit.

How many square feet does the Core 400S really cover? 358 sq ft at 4.8 air changes per hour on the current listing (403 sq ft on the original spec). Treat the 1,718 sq ft “1 ACH” figure as a best-case maintenance number, not a room rating.

Do the Core 400S and 600S have an ionizer or produce ozone? Neither has an ionizer. Both are CARB certified and rely purely on mechanical filtration plus activated carbon.

Is the Core 600S too loud for a bedroom? Its quoted floor is 26 dB in sleep mode, which is quiet but not silent. In a small bedroom the 400S at 22 dB is the better sleeper. In a large bedroom the 600S may still win, because it hits your target air quality without climbing the fan curve.

Do both models work with the VeSync app? Yes — scheduling, auto mode, filter-life tracking and voice control through Alexa or Google Assistant are identical across both.

Conclusion

This is a room-size decision dressed up as a product decision. Measure the space, use the 4.8 ACH coverage figure, and pick the model whose rating comfortably exceeds it. The Core 400S is the right answer for bedrooms, offices and normal living rooms; the Core 600S earns its place in open-plan spaces and basements where the smaller unit would spend its life at full tilt. Both give you the same filtration, the same app and the same absence of ozone-producing gimmicks — you are only buying airflow. If you are still deciding whether a purifier belongs in your home at all, start with are air purifiers worth it.