Buying guide
Choosing an Air Purifier: Room Size, CADR and Energy Use
Short answer
Start with your room: ENERGY STAR lists a recommended room size for each certified purifier, from 358 sq ft for the Levoit Core 400S up to 606 sq ft for the Levoit Core 600S. Then compare CADR and yearly energy use on the same basis, and decide whether Wi-Fi and an automatic mode matter to you. Every figure below is ENERGY STAR's own data; it covers particle removal, not odors, gases or health outcomes.
Who should pick what
- Bedroom or small room of about 360 sq ft Levoit Core 400S air purifier
- 358sq ft
- 231CADR
- 237kWh/yr
- Room of about 385 sq ft Winix C610 air purifier
- 384sq ft
- 248CADR
- 235kWh/yr
- Large room of about 580 sq ft Coway Airmega 400 air purifier
- 583sq ft
- 376CADR
- 366kWh/yr
- Open or very large room of about 600 sq ft Levoit Core 600S air purifier
- 606sq ft
- 391CADR
- 387kWh/yr
Side-by-side comparison
| Criterion | Levoit Core 400S | Winix C610 | Coway Airmega 300 | Coway Airmega 400 | Levoit Core 600S |
|---|---|---|---|---|---|
| Recommended room size | 358 sq ft | 384 sq ft | 488 sq ft | 583 sq ft | 606 sq ft |
| CADR (smoke / dust / pollen) | 231 / 240 / 259 cfm | 248 / 252 / 262 cfm | 315 / 333 / 360 cfm | 376 / 384 / 409 cfm | 391 / 398 / 436 cfm (best in this row) |
| Energy use | 237 kWh/yr | 235 kWh/yr (best in this row) | 314 kWh/yr | 366 kWh/yr | 387 kWh/yr |
| Filter type | HEPA-Type | HEPA-Type | Composite Filter; second filter: Composite Filter | Composite Filter; second filter: Composite Filter | HEPA-Type |
| Connectivity and auto mode | Wi-Fi connected; automatic mode: Air Quality Sensor,Timer | Wi-Fi connected; automatic mode: Air Quality Sensor | Not connected; automatic mode: none listed | Not connected; automatic mode: Air Quality Sensor | Wi-Fi connected; automatic mode: Air Quality Sensor,Timer |
| Ozone emissions | 0 ppb | 1 ppb | 0 ppb | 0 ppb | 0 ppb |
| ENERGY STAR | Yes | Yes | Yes | Yes | Yes |
All figures are from ENERGY STAR's certified room air cleaner data (queried 2026-11-06). Noise level, filter replacement cost and warranty are not in that data, so we leave them out rather than guess. Highlighted = best value in the row: highest CADR, IEF, CEER, run time or suction; lowest yearly energy use or weight. Sources for every figure are listed under “Sources” below.
CADR (smoke), cfm: higher cleans air faster
Recommended room size, sq ft
Yearly energy use, kWh: lower is cheaper to run
How we compared: key criteria
- Room sizeENERGY STAR publishes a recommended room size for each certified model. Pick a model sized to the room: ENERGY STAR notes larger models use more energy, and its CADR chart is only an estimate.
- CADR, and what it measuresCADR (clean air delivery rate, in cfm) measures how quickly a unit delivers filtered air; ENERGY STAR lists it separately for smoke, dust and pollen, which are particles. A higher CADR serves a larger area. ENERGY STAR's CADR chart assumes an 8-foot ceiling, and it advises a higher CADR if your ceilings are higher.
- Energy useENERGY STAR says a standard room air cleaner running continuously uses about 394 kWh per year. The six models in this series list between 235 and 387 kWh per year, and the figure rises with room size.
- Filter typeENERGY STAR lists the filter as “HEPA-Type” for the Levoit and Winix C610 models and as a “Composite Filter” for the Coway models. These are the program's labels, not a test result, and the data does not say how long a filter lasts or what a replacement costs.
- Wi-Fi and automatic modeThe Levoit models and the Winix C610 are listed as Wi-Fi connected with an air-quality-sensor mode; the Coway Airmega 400 has a sensor mode without Wi-Fi, and the Airmega 300 lists neither. Decide whether an app or sensor mode is worth the extra complexity for you.
Our picks
Smaller room: Wi-Fi, sensor mode
Levoit Core 400S air purifier
- 358sq ft
- 231CADR
- 237kWh/yr
Why we'd pick it: 358 sq ft recommended room size, CADR 231 / 240 / 259 cfm (smoke / dust / pollen), 237 kWh per year, Wi-Fi and an air-quality-sensor mode, 0 ppb ozone emissions.
Skip it if… your room is larger than about 360 sq ft, or you want the filter spec ENERGY STAR lists for the Coway models; check the box code, since ENERGY STAR also lists a 363 sq ft Levoit row.
View on Amazon — Levoit Core 400S air purifier on Amazon.comSmaller room: Winix with an auto mode
Winix C610 air purifier
- 384sq ft
- 248CADR
- 235kWh/yr
Why we'd pick it: 384 sq ft, CADR 248 / 252 / 262 cfm, 235 kWh per year, Wi-Fi and a sensor-driven automatic mode, HEPA-Type filter.
Skip it if… you want zero ozone emissions on paper — ENERGY STAR lists 1 ppb for the C610 — or you do not want a bundle: the Amazon listing includes two years of replacement filters.
View on Amazon — Winix C610 air purifier on Amazon.comMid-large room: simplest controls
Coway Airmega 300 air purifier
- 488sq ft
- 315CADR
- 314kWh/yr
Why we'd pick it: 488 sq ft, CADR 315 / 333 / 360 cfm, 314 kWh per year, 0 ppb ozone emissions, no Wi-Fi.
Skip it if… you want an automatic mode or an app: ENERGY STAR lists neither for this model.
View on Amazon — Coway Airmega 300 air purifier on Amazon.comLarge room: sensor mode, no app
Coway Airmega 400 air purifier
- 583sq ft
- 376CADR
- 366kWh/yr
Why we'd pick it: 583 sq ft, CADR 376 / 384 / 409 cfm, 366 kWh per year, air-quality-sensor automatic mode, 0 ppb ozone emissions.
Skip it if… you want Wi-Fi control, which it lacks, or a smaller room; the larger unit uses more energy than a smaller one would.
View on Amazon — Coway Airmega 400 air purifier on Amazon.comLargest room in this set
Levoit Core 600S air purifier
- 606sq ft
- 391CADR
- 387kWh/yr
Why we'd pick it: 606 sq ft, CADR 391 / 398 / 436 cfm, 387 kWh per year, Wi-Fi and a sensor mode, 0 ppb ozone emissions.
Skip it if… your room is under about 450 sq ft; ENERGY STAR notes larger models use more energy and an oversized unit does not make a small room cleaner in any way its data measures.
View on Amazon — Levoit Core 600S air purifier on Amazon.comDownsides and when not to buy
- ENERGY STAR's data covers particle removal. It says nothing about odors, gases or smoke smell, and the EPA does not endorse manufacturers' health claims.
- Noise level, filter replacement cost and warranty are not in the data, and they differ a lot between models; check each manufacturer's page before buying.
- Recommended room sizes assume 8-foot ceilings; higher ceilings call for a higher CADR.
When the pricier option isn't worth it
A larger purifier is not worth the extra energy if your room is below its recommended size: ENERGY STAR notes larger models use more energy, so choose one sized to the room rather than the biggest.
Who should skip this product type
Skip a portable purifier as the main fix if the problem is gases, odors or a source you can remove (such as smoking indoors); this page's data cannot show a purifier handles those.
Extra costs, installation and compatibility
- Ongoing costs
- Electricity is in the table. Replacement filters are a recurring cost and we do not print prices; the Coway models list two composite filters in ENERGY STAR's data, so look up both. The Winix C610 on Amazon is sold as a bundle with two years of filters.
- Installation and space
- No installation is needed beyond a free outlet and open space around the intake; ENERGY STAR's data does not give dimensions or weight, so check the manufacturer's page for your space.
- Compatibility
- All six models listed in this series are certified for the US market (ENERGY STAR lists United States and Canada). Wi-Fi models need a home network; the Coway Airmega 400 and 300 do not list Wi-Fi.
Frequently asked questions
How do I choose an air purifier size?
Use the room's square footage. ENERGY STAR gives each certified model a recommended room size and says to choose one sized to the room; its CADR chart assumes 8-foot ceilings.
Does a higher CADR mean cleaner air?
A higher CADR means the unit delivers filtered air faster and can serve a larger area, according to ENERGY STAR. It measures particles, not odors or gases.
Are the Amazon listings the same as these ENERGY STAR models?
We matched them by model name and code. Two differ in small ways: the Winix C610 listing is a filter bundle, and Amazon prints the Coway as AP-2015F(G). Check the code on the page before buying.
View on Amazon
Levoit
Levoit Core 400S air purifier
- 358sq ft
- 231CADR
- 237kWh/yr
Mid-size smart purifier with an air-quality sensor and Wi-Fi.
Amazon lists this as Model Number Core 400S (Model Name Core 400S-P). ENERGY STAR lists two Levoit rows; the figures here are the row named “Core 400S” (358 sq ft). The other row, LAP-C401S-WUSR, is rated 363 sq ft, so check the model code on the box.
View on Amazon — Levoit Core 400S air purifier on Amazon.comWinix
Winix C610 air purifier
- 384sq ft
- 248CADR
- 235kWh/yr
Mid-size Winix with Wi-Fi and a sensor-driven automatic mode.
This Amazon listing is a bundle: the C610 purifier plus two years of replacement filters. The purifier is included; the filters add to what you pay.
View on Amazon — Winix C610 air purifier on Amazon.comCoway
Coway Airmega 300 air purifier
- 488sq ft
- 315CADR
- 314kWh/yr
Mid-to-large room Coway; no automatic mode listed.
View on Amazon — Coway Airmega 300 air purifier on Amazon.comCoway
Coway Airmega 400 air purifier
- 583sq ft
- 376CADR
- 366kWh/yr
Large-room Coway with a sensor-driven automatic mode.
Amazon prints the model number as AP-2015F(G); ENERGY STAR lists AP-2015F. A second Amazon listing for the Airmega 400 (B01C9RIACG, model 111012) exists; we link the AP-2015F one.
View on Amazon — Coway Airmega 400 air purifier on Amazon.comLevoit
Levoit Core 600S air purifier
- 606sq ft
- 391CADR
- 387kWh/yr
Larger Levoit with Wi-Fi and an air-quality sensor.
Amazon's listing shows model code LAP-C601S-WCA; ENERGY STAR files that code under the same certification as LAP-C601S-WUS, which is the row used here.
View on Amazon — Levoit Core 600S air purifier on Amazon.comLinks to Amazon.com are plain product links. We may earn a commission in the future if we join affiliate programs; this never decides what we recommend. Prices and availability change, so we don't print them — check the current details on Amazon. See our Affiliate Disclosure.
Research method, sources and review date
Research-based comparison: we compare manufacturer specifications, user manuals and published guidance, and note where a figure is a manufacturer claim. We do not test products in a lab. Figures come from ENERGY STAR's certified room air cleaner data (queried 2026-11-06); sizing guidance comes from ENERGY STAR. Amazon.com was checked only to confirm each model exists and to find its listing, not as a source of specifications. How we compare · Editorial policy
Sources
- ENERGY STAR certified room air cleaners data: Levoit Core 400S (data.energystar.gov, queried 2026-11-06)
- ENERGY STAR certified room air cleaners data: Winix C610 (data.energystar.gov, queried 2026-11-06)
- Winix America: C610 4-stage True HEPA air purifier product page (winixamerica.com, read 2026-11-06)
- ENERGY STAR certified room air cleaners data: Coway Airmega 300 (AP-1515H) (data.energystar.gov, queried 2026-11-06)
- ENERGY STAR certified room air cleaners data: Coway Airmega 400 (AP-2015F) (data.energystar.gov, queried 2026-11-06)
- ENERGY STAR certified room air cleaners data: Levoit Core 600S (LAP-C601S-WUS) (data.energystar.gov, queried 2026-11-06)
- ENERGY STAR: Air Cleaners (buying guidance, CADR and room-size chart)
Update log
- — Rebuilt (IPK-BUILD-5) around models confirmed to exist on Amazon.com. Figures come from ENERGY STAR certified-product data and, where we could read one, the manufacturer page; where a source does not state a figure we say so. Models not found on Amazon.com were removed from the picks.