20x25x1 air filter
A 20x25x1 filter is a nominal size. Five brands on this page list it between 19.5 x 24.5 x 0.75 and 19.75 x 24.75 x 0.75 inches, so measure your slot and compare it to the brand you plan to buy.
- Printed (nominal)
- 20" x 25" x 1"
- Actual, by brand
- 5 filters listed below
- Spread between brands
- 0.25" wide, 0.25" tall, 0.06" deep
- Face area (nominal)
- 3.47 sq ft
Actual size by brand
| Brand | Width | Height | Depth | Source |
|---|---|---|---|---|
| Filterbuy | 19.5" | 24.5" | 0.75" | [1] |
| Nordic Pure | 19.5" | 24.5" | 0.75" | [2] |
| AIRx (Discount Filters) | 19.5" | 24.5" | 0.75" | [3] |
| Filtrete | 19.68" | 24.68" | 0.81" | [4] |
| Aerostar | 19.75" | 24.75" | 0.75" | [5] |
MERV options
| Brand | MERV ratings sold at this size | Source |
|---|---|---|
| Filterbuy | 8, 11, 13 | [1] |
| Nordic Pure | 6, 7, 8, 10, 11, 12, 13, 14, 16 | [2] |
| AIRx (Discount Filters) | 7, 8, 11, 13 | [3] |
| Filtrete | 11 | [4] |
| Aerostar | 8 | [5] |
What MERV means: EPA, "What is a MERV rating?"
Listed prices
Prices change often. These are what each seller listed on the date shown.
| Seller | MERV | Pack | Price | Each | Checked | |
|---|---|---|---|---|---|---|
| Discount Filters | 8 | 4 | $49.95 | $12.49 | Oct 21, 2026 [3] | Check price |
| Nordic Pure | 8 | 6 | $55.49 | $9.25 | Oct 21, 2026 [2] | |
| Amazon (Filtrete) | 11 | 2 | $22.99 | $11.49 | Oct 21, 2026 [4] | Check price |
Printed size vs actual size
The 20x25x1 on the label is a nominal size. The filter you get is cut smaller so it slides into the slot. Filterbuy, Nordic Pure and the AIRx line at Discount Filters all list 19.5 x 24.5 x 0.75 inches. Filtrete's Amazon listing gives 19.68 x 24.68 x 0.81, and Aerostar lists 19.75 x 24.75 x 0.75.
How much the brands differ
Width and height vary by 0.25 inches across these five brands (19.5 to 19.75, and 24.5 to 24.75). Depth runs from 0.75 to 0.81 inches, with Filtrete the thickest of the group. On a filter this large, a quarter inch of gap along each edge adds up to a lot of air that can go around the filter instead of through it.
How to measure and what to buy
Read the size on your old filter, then measure the slot: width, height and depth. If it is close to 19.75 x 24.75, a larger-cut brand such as Aerostar fills more of it. If the slot is tight or nearer 19.5 x 24.5, pick a brand that lists 19.5 x 24.5. If your number falls in between, buy the smaller one, because a filter that is too big will not go in. If the slot depth is tight, note that the Filtrete listing is 0.81 inches thick.
Depth matters
The 1 inch filters on this page are 0.75 to 0.81 inches thick. A 1 inch slot will not take a 2 or 4 inch filter with the same 20x25 face. Filtrete lists its MERV 11 version as MPR 1000.
Questions
What is the actual size of a 20x25x1 filter?
It depends on the brand. Filterbuy, Nordic Pure and AIRx list 19.5 x 24.5 x 0.75 inches, Filtrete lists 19.68 x 24.68 x 0.81, and Aerostar lists 19.75 x 24.75 x 0.75.
How much do 20x25x1 brands differ in size?
Across the five brands on this page, width and height differ by up to 0.25 inches, and depth by up to 0.06 inches.
Can I put a 20x25x4 filter in a 20x25x1 slot?
No. The 1 inch filters on this page are 0.75 to 0.81 inches deep, and a 1 inch slot has no room for a filter 2 or more inches deep.
Similar sizes
Not sure which you have? How to read and measure your filter.
Sources
- Filterbuy 20x25x1 air filter product page, read Oct 21, 2026
- Nordic Pure 20x25x1 air filter product page (actual size and price shown per MERV and box size), read Oct 21, 2026
- Discount Filters 20x25x1 furnace air filters, read Oct 21, 2026
- Filtrete 20x25x1 Air Filter, MERV 11, MPR 1000, 2 HVAC Filters (Amazon), read Oct 21, 2026
- Aerostar 20x25x1 Air Filter MERV 8, 12 Pack (Amazon), read Oct 21, 2026