LEVOIT Core 400S vs Core 600S

Most comparisons of these two treat the 600S as the upgrade and the 400S as the budget option. That framing is wrong in a way that costs money. They are the same machine at two sizes, and buying the larger one for a room that does not need it buys nothing except a bigger electricity bill and a few more decibels.

Electricity costs on this page use 18.34¢ per kWh, the U.S. average residential price for June 2026 from the U.S. Energy Information Administration, Electric Power Monthly, Table 5.3. Your rate is on your bill and is probably not this one; multiply the kWh figure by your own rate and you have your number.

Both units are in the ENERGY STAR register and neither is in AHAM’s. Both are classified “Fan and Filter”, meaning no ion generator, no plasma stage, no UV lamp. Both measure 0.00 ppb ozone. Both have their filters recorded as HEPA-Type rather than HEPA, in spite of “True HEPA” appearing on the packaging of each.

Both also carry exactly the same coverage gap. LEVOIT advertises 1,718 square feet for the 400S and 2,909 for the 600S; the certified figures are 358 and 606. Divide either pair and you get the same number — 4.8, which is the ratio between a coverage claim computed at one air change per hour and the certified figure computed at the 4.8 air changes the seal is based on. The company is not hiding it: both numbers appear on both product pages.

391 against 231 smoke CADR is 160 more cubic feet of clean air per minute, or 69% more. ENERGY STAR converts that into 606 certified square feet against 358 — the same 69%, because certified room size is a linear function of CADR.

AHAM’s own rule says an air cleaner’s CADR should be at least two-thirds of the room’s floor area, assuming an eight-foot ceiling. So a 300 square-foot room asks for 200 CFM and the 400S delivers 231. A 500 square-foot room asks for 334 and the 400S does not reach it, while the 600S does.

Certified room size is a single threshold, and thresholds hide the shape of the trade. Air changes per hour show it. Both figures below are the same arithmetic the register uses — CADR times 60, divided by the room volume at an eight-foot ceiling — and the 4.8 column is the rate LEVOIT’s own certified coverage claim is based on.

Read down the table and the crossover is obvious. Under about 358 square feet the 400S is already delivering more air changes than the certification asks for, and the 600S is delivering more still — for money you have already spent and money you will keep spending. Over 358, the 400S drops below the certified rate and the extra output is doing real work.

The 600S uses 387 certified kWh a year against the 400S’s 237, which is $71 against $43 — about $28 a year of difference at the U.S. average rate.

That is 63% more electricity for 69% more air, which means the 600S is fractionally more efficient per unit of clean air delivered, not less: the register puts its Integrated Energy Factor at 6.0 CFM per watt against the 400S’s 5.8. So the usual objection — that the big one is a power hog — is not true as stated. The waste is not in the machine, it is in buying capacity for a room that does not need it.

Electricity is also only half the bill. LEVOIT publishes a replacement filter price for the 400S and the 600S cartridge is listed higher, but our registry carries a published figure for only one of the two, so we are not going to print a like-for-like filter comparison we cannot source both halves of. How filter cost changes a three-year total is worth reading before you commit to either.

LEVOIT publishes 22-52 dB for the 400S and 26-55 dB for the 600S. Four decibels at the quiet end is not nothing in a bedroom, and it compounds with the sizing point: in a room the 400S covers, the 400S can hold the certified rate at a lower fan speed than the 600S needs to be interesting at all.

These are manufacturer figures rather than certified ones — neither register publishes noise — so treat them as directionally right rather than exact. If the machine is going next to a bed, what the dB numbers do and do not tell you is the fuller answer.

If your room is materially larger than 606 square feet, neither of these clears AHAM’s rule and the honest answer is a bigger machine or two machines — the large-room roundup ranks the units that do. If you do not know your square footage, do not guess it: the size calculator takes the room dimensions and ceiling height and returns the CADR you need, which makes this entire page a lookup rather than a decision.

And if what you actually wanted was a comparison against the other machine everyone recommends in this bracket, the 400S has already been through that one — Core 400S against the Coway Airmega Mighty turns on whether a model appears in any register at all, which is a sharper question than this page gets to ask.