Furnace filter size

16x25x1 Furnace Filters

The one size in this catalog where the same slot is offered at two clearly different ratings.

Depth — 0.75–0.81 in stated, against a nominal 1 in

Sixteen by twenty-five is the second most common one-inch slot after 20x25x1, and this catalog carries it at two ratings — MERV 8 and MERV 11 — which makes it the clearest place on the site to see the rating trade-off in one nominal size.

The two listings state actual sizes about 0.18 in apart on each face: 15.50 x 24.50 x 0.75 in against 15.68 x 24.68 x 0.81 in. The finer-rated filter is also the physically larger frame, which is a coincidence of manufacturer rather than a rule.

A 16-inch face gives less media area than a 20-inch one at the same depth. That matters for how quickly a filter loads, and it is another reason the replacement interval is worth taking seriously at this size.

What this catalog carries at 16x25x1

2 filters, at MERV 8 and MERV 11.

Stated figures at 16x25x1

Listing	Actual size stated	MERV	MPR	Pack
Filterbuy 16x25x1 MERV 8, 6-pack	15.50 x 24.50 x 0.75 in	MERV 8	Not stated	6 per box
Filtrete 16x25x1 MERV 11, 4-pack	15.68 x 24.68 x 0.81 in	MERV 11	MPR 1000	4 per box

Filterbuy 16x25x1 MERV 8, 6-pack
Actual size stated
15.50 x 24.50 x 0.75 in
MERV
MERV 8
MPR
Not stated
Pack
6 per box
Filtrete 16x25x1 MERV 11, 4-pack
Actual size stated
15.68 x 24.68 x 0.81 in
MERV
MERV 11
MPR
MPR 1000
Pack
4 per box

Check the one you have first

Read the nominal size printed on the frame of the filter currently in the slot.
Measure the frame with a tape: 16-inch faces are easy to confuse with 16.5 and 18 inch variants that also exist.
Note the arrow direction on the old frame before it comes out.
Check the stated actual size in the listing against your measurement, and check the depth separately — the two listings here differ on it.

The arrow, and the schedule

With two ratings available at this size, people often swap between them mid-year and lose track of orientation in the process. The arrow is printed on the frame of both. It points toward the blower, every time, whatever the rating on the label says.

Follow the filter manufacturer interval and the system documentation. A 16-inch face carries less media than a 20-inch one at the same depth, so at equal running hours this size reaches the end of its useful life sooner rather than later.

A higher MERV rating is not an upgrade by default

The MERV 11 option at this size resists airflow more than the MERV 8 one. The equipment manufacturer publishes the filter rating and pressure drop the system was designed around, and that document is what decides between them. Never select the finer rating simply because both are available at your size. If the documentation cannot be found, a licensed HVAC professional can advise on the specific equipment.

The 16x25x1 filters in this catalog

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Filterbuy 16x25x1 MERV 8, 6-pack

Nominal 16x25x1
Actual 15.50 x 24.50 x 0.75 in
MERV 8
6 per box

The MERV 8 answer in 16x25x1, with a stated actual size of 15.50 x 24.50 x 0.75 in. Set beside the MERV 11 filter in the same nominal size, the frames differ by roughly 0.18 in on each face — small on paper, and enough to change how a filter seats in a slot with rails. Six to a box, electrostatic pleated, US made per the listing.

What the listing supports, and what it does not

Actual size is stated, which allows a direct comparison with other 16x25x1 listings
MERV 8 keeps resistance lower than the MERV 11 filter in the same slot size
Six per box is the largest quantity offered in this nominal size here
Electrostatic pleated construction and US manufacture are stated
A 15.50 in face is the smallest stated 16-inch dimension in this catalog
Stated depth is 0.75 in against a nominal one inch
MERV 8 will not satisfy anyone specifically shopping for a finer rating

Best forA 16x25x1 slot where the priority is not restricting the blower.

Check it on Amazon

Filtrete 16x25x1 MERV 11, 4-pack

Nominal 16x25x1
Actual 15.68 x 24.68 x 0.81 in
MERV 11
MPR 1000
4 per box

16x25x1 with a stated actual size of 15.68 x 24.68 x 0.81 in, and MPR 1000 alongside MERV 11. The 0.32 in shortfall on the 16-inch face is the same proportional gap this manufacturer states across its one-inch line, which makes the numbers at least internally consistent. Four per box.

What the listing supports, and what it does not

Actual dimensions are stated on all three axes
Four per box covers a full year on a quarterly schedule
MERV 11 and MPR 1000 both appear, so either scale can be matched
Stated depth of 0.81 in is at the fuller end for a one-inch filter
MERV 11 media raises resistance compared with the MERV 5 to 8 group
The narrower 16-inch face means less media area than a 20-inch filter of the same depth
Two rating scales on one label is still two scales, not one converted into the other

Best forA 16x25x1 return in a system whose manufacturer documentation permits MERV 11.