PerfectFit Filter Sizing

What size PerfectFit Filter should you order?

It is important to order the correct size. If ordered improperly, the filter can be replaced with the correct size or returned for a 15% restocking fee and the difference, if any, in price. Return shipping is borne by the client so please make sure your sizing is correct. If you have any questions, call 800.728.7206 during normal business hours (EST) or email support [at] bestlivingsystems [dot] com


Measuring your filter frame is helpful to determining what size filter you should use. However, the easiest way is to use the same size filter you are currently using. Typically, the size of the filter is printed on the outside edge, on the cardboard, and printed as height X width X depth in inches (ex., 14"x24"x1"). If you have that information, you have what you need to order. Simply click here and order the correct size.


Measuring your filter frame or the filter you are currently using is easy, but the measurements are sometimes deceptive. ALL of the PerfectFit Filters sold on this website are rounded UP to the nearest inch, so for example 24 1/4" becomes 25", 14 3/4" becomes 15", etc. The depth of the filter is always 1" even if your opening or existing filter is from 3/4" to 2" deep. Here is a step-by-step for actually measuring both the frame and the filter--either will be accurate, so simply do which is the easiest and most accessible:

FILTER - Take the filter out of the system and stand it on end on the floor. It doesn't matter which end you stand it on, all as the filter is a parallelogram and opposite sides are equal. With a measuring tape, measure from the floor to the top edge of the filter and round up to the higher inch (ex., 14 3/4" becomes 15"). Measure the distance across the filter (from left to right) and round up to the higher inch (24 1/4" becomes 25"). Now you have it... you would order a 15"x25"x1" PerfectFit Filter.

FRAME - This is a little more difficult because some frames have bracing or rivets on the inside of the frame that obstruct the oversized filter. However, when you use the PerfectFit Filter, these obstructions are minor because the PerfectFit Filter has an internal frame which is a bit smaller than the cardboard or aluminum frame you may be used to. So again, measure across the diameter of the frame going in each direction and round up to the higher inch to get the correct measurement for the PerfectFit Filter you need.

SPECIALTY SIZES - Even though the PerfectFit Filter does not come is unusual (non-standard) sizes (see the list below), in many cases the standard sizes will fit the opening without blow-by. For instance, if you have measured a 24"x40" opening, two 24"x20" filters would fit nicely and cover the return intake without obstructing air flow or allowing blow-by.

In any event, filter sizes are standardized but can be a little misleading. For example, a 1" filter actually doesn't look a full inch deep and, if you measured it with a tape, yard stick or ruler, it wouldn't be. However, you still need a 1" filter.

DID YOU KNOW? - When sizing your filter, height and width are interchangeable because whether the register is vertical (portrait) or horizontal (landscape), the PerfectFit Filter will fit perfectly. For example, a 14"x30"x1" filter is the same size as a 30"x14"x1" filter.

HOW TO ORDER - Pick your filter size(s), sign up for the subscription, with an initial cost as low as $39.99 and monthly payments of $6.00, and your convenience pack (4 filters) will be shipped to you within a few days. Install the first filter, and we'll send you an email when it's time to replace it. At the end of the year we will automatically ship you a new convenience pack of 4 filters for the next year while continuing only the low monthly charge.