A 16x25x4 MERV 13 filter fits a four inch furnace slot, and it measures 15.5 by 24.5 by 3.625 inches in your hand. We ship the 16x25x4 MERV 13 pleated air filter in a box of three, and one box covers three filter changes.

You can confirm the fit in about five minutes with the old filter in your hand. Check the size printed on the edge of the old frame first. Then look up the top MERV rating in your furnace manual. When the manual allows MERV 13, this is the box to order. When the manual stops at MERV 11, we stock the 16x25x4 MERV 11 pleated air filter in the same box of three.

Written by the Water Filters FAST filter experts. Reviewed by Phil McNamara, owner, Water Filters FAST. Updated October 2026.

Read the size on the old frame

Pull the old filter out of the furnace. Look at the edge of its frame, where the size shows as three numbers. A filter for this slot shows 16x25x4. The first two numbers give the face of the filter in inches, and the 4 gives the depth. Take a photo of the frame with your phone, and you have the size on hand when you order.

Those three numbers make up the size name, and the actual size is a little smaller. A 16x25x4 filter measures 15.5 by 24.5 by 3.625 inches, because the size name rounds each number up to the next whole inch. Our product page puts both sizes in its title, and you can match the filter by either one.

If the old frame also shows a MERV rating, write it down. That number is the rating your furnace used last, and you compare it with the manual in a later step. Do this check when you change the filter at the start of heating season, and you order the right box the first time.

The size on your old filter overrules any table in this post, because that filter came out of your own furnace. A frame with a different set of numbers needs a different filter. Our MERV 13 air filters collection shows the MERV 13 filters we stock in other sizes. If your size is missing there, call 855-789-FAST with the three numbers from the frame.

Measure the filter and the slot

Use a tape measure when the old frame is worn or torn. Measure the face of the old filter across the long side and the short side. Then measure the depth from the front of the frame to the back. On a tape measure, 3.625 inches is three and five eighths inches. A face close to 15.5 by 24.5 inches and a depth close to 3.625 inches confirm the 16x25x4 size.

Next, measure the slot across its long side and its short side. Measure the depth of the slot from its opening to the back as well. The new filter slides into the slot at its full depth of 3.625 inches, and a four inch slot takes that depth. A slot less than 3.625 inches deep needs a thinner filter, and our filter experts can help you find that size.

Write your numbers down before you order. Keep them with the furnace manual, and you have them ready for the next box.

What a 16x25x4 MERV 13 filter catches

The MERV number tells you how small a particle the filter can catch. Trane says a MERV 13 filter can catch particles down to 0.3 to 1 micron in size. It puts MERV 11 at 1 to 3 microns. A smaller micron number means a smaller particle. MERV 13 reaches into the smaller range, and MERV 11 stops at the larger one. You can compare both ranges on Trane's MERV comparison page.

Our 16x25x4 MERV 13 filter removes over 75 percent of airborne particles between 0.3 and 1.0 microns on the first air exchange. For particles from 1.0 to 3.0 microns, it removes over 90 percent.

Each filter in the box has pleats and an electrostatic charge. The charge works like a magnet. It draws airborne particles to the filter.

MERV 13 or MERV 11 in the same four inch slot

We stock both ratings in the 16x25x4 size. Both boxes fit the same slot. Each box comes with three filters at the same actual size, and both are in stock for fast shipping. Your choice depends on the top rating your furnace takes.

Trane says some systems cannot take a MERV 13 filter, because the filter can restrict airflow. Check the top rating in your furnace manual before you choose. If the manual is missing, ask your installer for that number before you place the order.

With MERV 13 or higher in the manual, order the MERV 13 box for the smaller of Trane's two particle ranges. With MERV 11 as the top rating, order the MERV 11 box for the same slot. Then compare the manual with the rating on your old frame. When the old frame shows MERV 11 and the manual allows MERV 13, you can move up to the MERV 13 box in the same size. When the old frame already shows MERV 13, reorder the same box.

Our MERV 11 air filters collection shows the MERV 11 filters we stock in other sizes, and our MERV 11 filter buying guide covers that rating in more detail. For a furnace whose manual lists MERV 8 as its top rating, we stock the 16x25x4 MERV 8 pleated air filter in the same box of three. Our guide to MERV 8 or MERV 11 compares those two ratings side by side.

How long a box of three lasts

Trane gives a range of 30 to 90 days between filter changes. When your furnace manual sets its own interval, follow the manual. Pick one interval inside the range and use it for every filter in the box.

At 30 days a filter, a box of three covers about three months. At 90 days a filter, the same box covers about nine months, and a box you open at the start of heating season lasts into the summer. Two boxes give you six filters, or about eighteen months of changes at that pace.

Write the install date on the frame of each new filter. The date tells you how many days the filter has been in, and you can see when the next change is due.

Order the next box when you put in the last filter from the current one. You then have a fresh filter on hand at the next change. The reorder takes one visit to the same product page, and the new box fits the slot you already measured.

Six steps to the right box for your furnace

Keep the old filter beside you for the first two steps.

1. Read the size on the frame of the old filter.
2. Measure the slot and the old filter with a tape measure.
3. Check the furnace manual for the top MERV rating.
4. Order the box that matches the size and the rating.
5. Write the date on the frame of each new filter.
6. Set a reminder for the next change inside Trane's range of 30 to 90 days.

Finish step 3 before you order, because you need the top rating from the manual to choose between the two boxes. Change the filter each time the step 6 reminder comes up. Then set the next reminder for the same interval.

Common questions about the 16x25x4 MERV 13 filter

Is MERV 13 too high for home use?

MERV 13 suits home use when your furnace manual lists MERV 13 or higher. In that furnace, the filter catches particles down to 0.3 to 1 micron in size. When the manual stops at MERV 11, our 16x25x4 MERV 11 box fits the same slot and comes in the same box of three.

How often should I replace a 16x25x4 MERV 13 filter?

Plan on a fresh filter every 30 to 90 days, which is the range Trane gives for air filters. Your furnace manual overrules that range when it sets an interval of its own. Each box of three covers three changes at any point inside the range.

What is the actual size of a 16x25x4 air filter?

The actual size of a 16x25x4 air filter is 15.5 by 24.5 by 3.625 inches. At 3.625 inches deep, the filter slides into a four inch furnace slot. Our 16x25x4 MERV 13 pleated air filter comes in a box of three at that actual size, and so does our MERV 11 box.

Order your 16x25x4 MERV 13 filters

Order the 16x25x4 MERV 13 pleated air filter in a box of three, and you get low prices and fast shipping. You also get 30-day returns and our satisfaction guarantee. When your manual stops at MERV 11, order the 16x25x4 MERV 11 box, and you get the same returns and guarantee. Save the product page on your phone, and you can reorder the same box when the reminder from step 6 comes up.

Call 855-789-FAST and talk it through with the filter experts before you buy.