Five year cost of owning the Coway unit

Quick answer

At $218.50 for the machine and $23.99 for a replacement filter, five years of ownership costs $314.46 if the filter is changed every 12 months, which is $62.89 a year and puts 31 percent of the total into filters rather than into the machine. Changing every six months instead takes the five year total to $434.41.

This listing does not state a replacement interval, so all three intervals are shown rather than one being chosen for it.

Five year cost of ownership at three replacement intervals
IntervalFilters boughtSpent on filtersFive year totalPer yearFilter share
Every 6 months9$215.91$434.41$86.8850 percent
Every 9 months6$143.94$362.44$72.4940 percent
Every 12 months4$95.96$314.46$62.8931 percent
The machine

COWAY Air Purifier for Home Up to 1,748ft2, HEPA Filter for Smoke, Allergies, Pet Dander, Odor, Air Quality Monitor, Auto&Eco Mode, Timer, Filter Indicator, 3yr Warranty, Mighty AP-1512HH, Black

$218.50 once. It can be credited with about 233 CFM, derived from the listing's own figures: 1748 sq ft at 1 air changes an hour, assuming an eight foot ceiling.

$218.50Check pricePrices change often

Prices move, and the five year arithmetic above moves with them.

The filter this machine actually takes

$23.99 each, and the table above is what that adds up to. This is the purchase that repeats, which is why it decides the real cost of the machine rather than the sticker price does.

Why the filter cost is the real number

Coway sells the machine at $218.50, which is the number on the shelf edge and the one people compare. Over five years at a 12 month interval the filters add $95.96, which is 31 percent of the total cost of owning it. A machine that is fifty dollars cheaper with a filter that is twenty dollars dearer is not cheaper, it is more expensive by the second year.

That is the whole argument for looking up the filter price before buying the machine rather than after. Proprietary filters are where the margin lives in this category, and the cheapest machines frequently carry the dearest filters relative to their price.

What is not in this total

Power. A purifier running continuously at fifty watts uses about 438 kilowatt hours a year, which at fifteen cents a unit is roughly sixty five dollars a year, or a third of the machine price again over five years. Running a larger machine at a lower speed is usually cheaper than running a small one flat out, because fan power rises steeply with speed.

Also missing: the pre-filter, which costs nothing if it is washable and is what keeps the interval above at the long end rather than the short one.

Common questions

How much does this purifier really cost?

The machine is $218.50, and over five years the filters add $95.96 at a 12 month interval, for a total of $314.46. That works out at $5.24 a month. Power is on top of that, and a machine drawing fifty watts continuously adds roughly sixty five dollars a year at fifteen cents a kilowatt hour.

Does the replacement interval really change the answer?

Substantially. Over five years this machine costs $314.46 at a twelve month interval and $434.41 at six months, because the number of filters bought roughly doubles. Interval is set by how dirty the air is as much as by the calendar, so a house with pets or a smoke season will sit at the shorter end.

Can I use a cheaper third party filter?

Sometimes, and the risk is the seal rather than the media. Air takes the easiest path, so a filter that does not seat properly in the housing lets air bypass the media entirely and the machine quietly stops filtering while still making noise. If you use one, look at how it sits in the machine rather than at the percentage printed on the box.

Is a washable pre-filter worth anything?

Yes, and it is the single cheapest way to extend the interval above. The pre-filter catches hair and coarse dust that would otherwise load the pleated stage, and washing it every few weeks is free. It does not replace the main filter, and no pleated HEPA filter can be washed and put back.

What does this machine deliver for the money?

It can be credited with about 233 CFM of clean air delivery, derived from the listing's own figures: 1748 sq ft at 1 air changes an hour, assuming an eight foot ceiling. At four and a half air changes an hour that suits a room of roughly 388 square feet with an eight foot ceiling.