SpecsyHome and maintenance
Never forget your air filter size again
You pull out the old filter, throw it away, and six months later cannot remember whether it was 20x20x1 or 20x25x1
- Size
- 20 x 25 x 1 in
- MERV
- 11
- Brand
- Filtrete
- Model
- 2200
- Bought at
- Local hardware shop
The size is printed on the thing you just binned
Filter sizes are printed on the cardboard frame, which goes in the bin at the exact moment you stop needing it and six months before you need it again.
Worse, a house often has more than one. The furnace filter is not the same as the one in the bedroom air purifier, and the extractor hood has its own. Three sizes, three brands, one vague memory.
So the filter goes unchanged for another two months, or you buy the wrong one and now own a filter that fits nothing you have.
What to put on a filter card
One card per filter, not one per house. They are different sizes and you will need to tell them apart.
- The exact size as printed on the frame, including the direction of airflow
- MERV or filtration rating, because a cheaper rating is a different product
- Brand and model number of the one that worked
- A photo of the old frame before you throw it out
- Where you bought it and what it cost, so you notice when the price doubles
Filters in an average home that all have different sizes
- Furnace or central air filter, usually the largest
- Air purifier cartridge, often a proprietary model number
- Extractor hood grease filter, measured in millimetres
- Car cabin filter, which has nothing to do with any of the above
- Vacuum HEPA filter, tied to the vacuum model rather than a size
Do this once, on the next change
- Photograph the frame before it goes in the binEvery number you need is printed on it, and the photo takes three seconds.
- Type the size into a cardWrite it the way it is printed, including the units. A filter labelled 20x25x1 in is not 20x25x1 cm.
- Set the reminder while you are thereThree months, six months, whatever the manufacturer says. This is the part that actually changes the outcome.
Questions people ask
Why not just measure the old one?
Nominal filter sizes are rounded. A filter sold as 20x25x1 usually measures about 19.5 by 24.5. Measuring and buying by your measurement is how people end up with the wrong one.
Can Specsy remind me when it is due?
Yes. Put the interval on the card and the reminder arrives on your phone without you thinking about it again.
What if I have several filters of the same type?
Give each card the room name. In the shop you open the room, not the guesswork.