The short answer
- About $913 to own over five years: $399 to buy, $158 in electricity, $356 in filters.
- It cleans faster than the Mighty and costs about $260 more to own across five years.
- Coway quotes coverage here at 4 air changes an hour. At the 4.8 it uses elsewhere in its own range, the figure is 389 sq ft.
Who this is for
The Airmega 250 makes sense in a room of up to about 390 square feet, or where you would rather have a single annual filter date than the Mighty’s two overlapping schedules. It is a better machine. The question this page exists to answer is whether it is $260 better across five years.
One inconsistency worth naming: Coway publishes this model’s coverage at four air changes an hour, while publishing the Mighty and the Airmega 400 at 4.8. The same manufacturer using two different bars inside one range makes its own products hard to compare. At 4.8, this one covers 389 square feet.
What the specifications actually say
CADR is 249 for smoke, 261 for dust and 230 for pollen, so meaningfully quicker than the Mighty’s 233, and it does it on 64 W against the Mighty’s 77 W. That is the better engineering. It is also, as the model below shows, the part of the bill that matters least.
The filter life is stated twice on the same page and not identically: the specification table says one year, the description says six to twelve months. We have costed it at one year, which is the more favourable of the two readings.
| Specification | Value | Source |
|---|---|---|
| CADR (smoke) | 249 CFM | Coway spec page, AHAM figures as published, retrieved 31 Aug 2026 |
| CADR (dust) | 261 CFM | Coway spec page |
| CADR (pollen) | 230 CFM | Coway spec page |
| Coverage at 1 ACH | 1,860 sq ft | Coway spec page |
| Coverage at 4 ACH | 465 sq ft | Published by Coway |
| Coverage at 4.8 ACH | 389 sq ft | Calculated from CADR 249 at an 8 ft ceiling |
| Power draw | 64 W | Coway spec page |
| Filter life | 1 year (page also says 6-12 months) | Coway spec page |
| Replacement Max2 filter | $89.00 | Coway store, retrieved 31 Aug 2026 |
| Noise | 22-54 dB(A) | Coway spec page |
| Price | $399 | Merchant listing at publication |
The cost nobody quotes
Five years, at the US average of $0.17 per kWh, running eight hours a day.
What it really costs over 5 years
Total$913
| Cost | Amount | How we got it |
|---|---|---|
| Purchase price | $399 | Street price at publication |
| Electricity | $158 | 186 kWh/yr at $0.17 per kWh |
| Filters & consumables | $356 | $71 per year |
| Total | $913 | $183 per year · $0.06 per session |
Running costs are 56% of the 5-year total. The sticker price is not the decision.
Electricity priced at $0.17 per kWh, the US residential average. Change the rate in the settings to match your utility. Consumable costs come from the manufacturer's published replacement schedule.
The $89 Max2 filter is the whole story. Four of them across five years is $356, against about $220 for the Mighty. Add the $159 difference in purchase price and you have almost exactly the $260 gap. Faster cleaning, more expensive to keep.
If Coway’s other reading is the right one and the filter needs replacing at six months, the consumables line doubles to about $712 and the five-year total passes $1,269. That single ambiguity is worth more money than the entire electricity bill.
Certifications, and what they cover
Frequently asked questions
Is the Airmega 250 worth the extra over the Mighty?
It cleans faster on less power, and it costs about $260 more to own across five years. Below roughly 360 square feet the Mighty already does the job.
What does the replacement filter cost?
$89.00 from Coway for the Max2 filter, rated at one year. Four of them across five years is $356.
What room size does it really cover?
About 389 square feet at 4.8 air changes an hour, calculated from the published CADR. Coway’s own 465 sq ft figure is measured at four air changes.
Why do you not test these yourself?
We are a research publication, not a lab. We verify third-party test data, publish the source next to every number, and calculate the costs manufacturers leave out.
