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6 Things Homeowners Miss When Ordering Custom Size Furnace Filters
Homeowners often assume that every furnace slot is a neat 16x25x1, but that's not always the case. Sometimes, you might need high-quality, affordable custom size furnace filters to keep your home feeling pleasant.
If you don't pay attention to this vital detail, off-the-shelf pads may leave gaps, rattle, or even block airflow. This is why custom size filters exist, and why we build them to the sixteenth of an inch here in Mississauga.
If you are interested in custom size HVAC filters but don't know where to start, you've come to the right place.
In this full guide to ordering custom size furnace filters online, you'll discover how to place an order, what MERV ratings mean, and more. We'll also tell you where to get the best air filters for furnace and how to find the best deals online.

Custom Size Filters: This Is When The Standard Pad Won’t Work
In the best case, a filter should slide in with a gentle push and seal on all four edges. If you find that it's bending the frame or light leaks around it, you should check out custom size filters.
-
Remodelled returns often shrink by three to four millimetres.
-
Variable-speed blowers depend on a deep media filter; swapping in a thin pad can raise static pressure and shorten motor life.
-
Brands like Honeywell or Lennox shave or add fractions to lock you into their cartridges.
These are all red flags and signs that you need to invest in custom furnace filters. You'll save money and frustration later on.
Nominal Vs. Actual Size: The Facts Are Here
When ordering custom size HVAC filters, you'll come across these two terms: Nominal and actual size. Take your time to learn the differences between these two, as that'll ensure that you order the best custom size furnace air filters.
In short, a store label will show the nominal dimensions, which are rounded to whole inches. That said, the actual size is what really matters. For example, a "16x25x5" could be:
-
15 ⅜ × 25 ½ × 5 ¼ (Carrier)
-
15 ⅞ × 24 ¾ × 4 ⅜ (often called a Honeywell five-inch)
-
15 ¾ × 24 ¼ × 4 ⅞ (Air Bear)
Get the best furnace filters in Canada from United Filter. We always make sure that you are familiar with the actual measurements before placing orders.
How to Measure for the Perfect Custom Size Furnace Filters?
For the best results and max accuracy, we always recommend measuring your furnace filter. This is simple and it only takes two minutes tops and a steel ruler.
-
Start by turning off the system.
-
Next, locate the old filter and pull it out gently.
-
Measure the opening: check its height, width, and depth.
-
Write down the exact numbers, like 15 ⅞ × 24 ¾ × 4 ⅜ in.
-
Order custom size filters today.
That's it! If you have any questions or doubts, we're here to help you. Purchase the highest-quality custom size furnace filters in Calgary for fresher, cleaner, and healthier air!
Best Air Filters for Furnace and MERV Ratings Explained
MERV ratings matter, and this word stands for "Minimum Efficiency Reporting Value". It was developed by ASHRAE, and it tells you on a 1-to-16 scale how well a filter traps particles during standardized laboratory tests.
-
MERV 5-8: These are basic pleated filters that work well for most homes. These filters can capture dust and mould spores.
-
MERV 9-11: MERV 11 furnace filters are a step up from MERV 8, and they are great for trapping pet dander and fine dust. So, if you live with pets or in an area more prone to pollution, these custom furnace filters could be an excellent option for you.
-
MERV 12-13: These are high-efficiency home filters that can capture smoke and bacteria-size particles. If you're looking for the most effective choice, these are the best air filters for furnace.
However, a higher MERV is not always better, as blowers have limits. Always check the maximum static-pressure specifications of your device before jumping from MERV 8 to MERV 13.

6 Things Homeowners Miss When Ordering Custom Size Furnace Filters
If you don't pay attention to these details, you might order the wrong custom size furnace filters. So, make sure you're aware of these six things, do a quick five-minute double-check, and only then order custom size air filters.
-
Nominal versus actual size matters: Again, this is key when choosing the right custom size filters. As you're aware now, the bold 16x25x5 on a box is rounded marketing. The real frame can be 15 ¾ × 24 ¾ × 4 ⅜ or something else entirely.
-
Buy the right depth: Keep in mind that Honeywell cabinets can take a 4 ⅜-in deep cartridge, Carrier needs 5 ¼ in, and Air Bear sits smack in the middle at 4 ⅞ inches. If you buy the wrong depth, the door won't latch.
-
Always check blower capacity before jumping to MERV 13: Higher MERV ratings can capture finer particles and provide higher resistance. Make sure your blower is capable of a higher rating, and only then get appropriate custom size furnace air filters.
-
Measure the sheet-metal ledge inside the rack: A common mistake when choosing the best custom size furnace filters is measuring the old filter instead of the cabinet opening. Remember that pleated frames can compress over time.
-
Don't ignore the airflow arrow and gasket seal: EPA installation guidance stresses that the arrow on the frame must point toward the blower and the frame must sit tight against all four rails. Otherwise, dust can bypass the media entirely.
-
Order in bulk: Another common error we see is ordering too few filters and paying repeat shipping. The truth is that five-inch pleats can weigh up to 1kg each.
Instead, buy a six-or twelve-pack to save extra costs. This way, you'll have a year's worth of changes and avoid emergency overnight fees.
Keep these seven checks on hand and your custom size filters will arrive once, fit once, and keep your blower running problem-free for months. Don't wait around and order the best custom size furnace filters Richmond, BC!
How to Order Custom Size Furnace Filters?
You're ready to order custom size filters. It's a fool-proof process that takes no time. Here's what you need to do.
-
Enter your nominal label (like 16x25x4).
-
Type the exact size from your ruler, and make sure it's correct.
-
Choose between MERV 8, 11, or 13.
-
Select a pack; The price usually drops per unit, so order in bulk for the most cost-effective option.
-
Checkout with flat-rate shipping across the US and Canada.
Order custom size furnace filters online in Canada and you'll receive your package in record time. Shipping is fast, reliable, and inexpensive.

Where Can I Find Discount Furnace Filters?
Usually, custom size air filters can be expensive as they're made to match your device perfectly. However, knowing where to find the best deals and discounts will help you enjoy maximum airflow and extend the life of your HVAC motor inexpensively.
The trick is to know where to find the best, premium-quality discount furnace filters.
Order top-notch custom size furnace filters in Canada from United Filter and get the best value on the market. Better yet, buy in bulk to keep a spare on hand in case you need it in the future.
Custom Size Furnace Filters and the Most Common Mistakes
These are some of the most common mistakes we see all the time when ordering custom size HVAC filters.
-
Gaps on the side: Always make sure you're ordering the correct custom size furnace filter online. The wrong depth can also make the filter rattle or prevent the door from properly closing.
-
Sudden whistle: This usually happens due to a collapsed pleat from high static pressure. We recommend moving down one MERV tier or installing a deeper frame.
-
Static shocks at vents: When the filter is overdue or the humidity is low, you might notice static shocks. It's best to run a humidifier and swap pads.
If you have any doubts, please reach out to us at (905) 403-0160 or leave a message via the contact us page. You can also check out our comprehensive blog section to learn more about ordering custom size furnace filters, how they work, MERV ratings, and more.
Custom Size Furnace Filters in Canada: FAQ
What is the difference between nominal and actual size?
In short, the nominal size is the rounded measurement that's printed on the filter label, like 16x25x1. The actual size is the precise dimension of the filter, which is typically smaller.
How do I know if I need a custom size furnace filter?
If the current filter isn't sliding in smoothly, bends, or leaves gaps, you might need a custom size. In most cases, older systems and remodelled spaces require non-standard sizes.
How often should I replace a custom size furnace filter?
For a 1-inch filter, it's best to schedule replacements every 60 to 90 days. For 4-to 5-inch, you can extend the timeframe to every 6 to 12 months. However, it all depends on the air quality in your home, whether you have pets and the local conditions.

Order Custom Size Filters Now
Measure your furnace filter once and breathe easier all year round. The best custom size filters will give your system the tight seal it needs, prevent dust from crossing over, and maintain smooth (and consistent) airflow.
Just search our shop for custom size filters. Your blower and your lungs will thank you! Order premium custom size furnace filters for cheap from United Filter today!
6 Things Homeowners Miss When Ordering Custom Size Furnace Filters
Homeowners often assume that every furnace slot is a neat 16x25x1, but that's not always the case. Sometimes, you might need high-quality, affordable custom size furnace filters to keep your home feeling pleasant.
If you don't pay attention to this vital detail, off-the-shelf pads may leave gaps, rattle, or even block airflow. This is why custom size filters exist, and why we build them to the sixteenth of an inch here in Mississauga.
If you are interested in custom size HVAC filters but don't know where to start, you've come to the right place.
In this full guide to ordering custom size furnace filters online, you'll discover how to place an order, what MERV ratings mean, and more. We'll also tell you where to get the best air filters for furnace and how to find the best deals online.

Custom Size Filters: This Is When The Standard Pad Won’t Work
In the best case, a filter should slide in with a gentle push and seal on all four edges. If you find that it's bending the frame or light leaks around it, you should check out custom size filters.
-
Remodelled returns often shrink by three to four millimetres.
-
Variable-speed blowers depend on a deep media filter; swapping in a thin pad can raise static pressure and shorten motor life.
-
Brands like Honeywell or Lennox shave or add fractions to lock you into their cartridges.
These are all red flags and signs that you need to invest in custom furnace filters. You'll save money and frustration later on.
Nominal Vs. Actual Size: The Facts Are Here
When ordering custom size HVAC filters, you'll come across these two terms: Nominal and actual size. Take your time to learn the differences between these two, as that'll ensure that you order the best custom size furnace air filters.
In short, a store label will show the nominal dimensions, which are rounded to whole inches. That said, the actual size is what really matters. For example, a "16x25x5" could be:
-
15 ⅜ × 25 ½ × 5 ¼ (Carrier)
-
15 ⅞ × 24 ¾ × 4 ⅜ (often called a Honeywell five-inch)
-
15 ¾ × 24 ¼ × 4 ⅞ (Air Bear)
Get the best furnace filters in Canada from United Filter. We always make sure that you are familiar with the actual measurements before placing orders.
How to Measure for the Perfect Custom Size Furnace Filters?
For the best results and max accuracy, we always recommend measuring your furnace filter. This is simple and it only takes two minutes tops and a steel ruler.
-
Start by turning off the system.
-
Next, locate the old filter and pull it out gently.
-
Measure the opening: check its height, width, and depth.
-
Write down the exact numbers, like 15 ⅞ × 24 ¾ × 4 ⅜ in.
-
Order custom size filters today.
That's it! If you have any questions or doubts, we're here to help you. Purchase the highest-quality custom size furnace filters in Calgary for fresher, cleaner, and healthier air!
Best Air Filters for Furnace and MERV Ratings Explained
MERV ratings matter, and this word stands for "Minimum Efficiency Reporting Value". It was developed by ASHRAE, and it tells you on a 1-to-16 scale how well a filter traps particles during standardized laboratory tests.
-
MERV 5-8: These are basic pleated filters that work well for most homes. These filters can capture dust and mould spores.
-
MERV 9-11: MERV 11 furnace filters are a step up from MERV 8, and they are great for trapping pet dander and fine dust. So, if you live with pets or in an area more prone to pollution, these custom furnace filters could be an excellent option for you.
-
MERV 12-13: These are high-efficiency home filters that can capture smoke and bacteria-size particles. If you're looking for the most effective choice, these are the best air filters for furnace.
However, a higher MERV is not always better, as blowers have limits. Always check the maximum static-pressure specifications of your device before jumping from MERV 8 to MERV 13.

6 Things Homeowners Miss When Ordering Custom Size Furnace Filters
If you don't pay attention to these details, you might order the wrong custom size furnace filters. So, make sure you're aware of these six things, do a quick five-minute double-check, and only then order custom size air filters.
-
Nominal versus actual size matters: Again, this is key when choosing the right custom size filters. As you're aware now, the bold 16x25x5 on a box is rounded marketing. The real frame can be 15 ¾ × 24 ¾ × 4 ⅜ or something else entirely.
-
Buy the right depth: Keep in mind that Honeywell cabinets can take a 4 ⅜-in deep cartridge, Carrier needs 5 ¼ in, and Air Bear sits smack in the middle at 4 ⅞ inches. If you buy the wrong depth, the door won't latch.
-
Always check blower capacity before jumping to MERV 13: Higher MERV ratings can capture finer particles and provide higher resistance. Make sure your blower is capable of a higher rating, and only then get appropriate custom size furnace air filters.
-
Measure the sheet-metal ledge inside the rack: A common mistake when choosing the best custom size furnace filters is measuring the old filter instead of the cabinet opening. Remember that pleated frames can compress over time.
-
Don't ignore the airflow arrow and gasket seal: EPA installation guidance stresses that the arrow on the frame must point toward the blower and the frame must sit tight against all four rails. Otherwise, dust can bypass the media entirely.
-
Order in bulk: Another common error we see is ordering too few filters and paying repeat shipping. The truth is that five-inch pleats can weigh up to 1kg each.
Instead, buy a six-or twelve-pack to save extra costs. This way, you'll have a year's worth of changes and avoid emergency overnight fees.
Keep these seven checks on hand and your custom size filters will arrive once, fit once, and keep your blower running problem-free for months. Don't wait around and order the best custom size furnace filters Richmond, BC!
How to Order Custom Size Furnace Filters?
You're ready to order custom size filters. It's a fool-proof process that takes no time. Here's what you need to do.
-
Enter your nominal label (like 16x25x4).
-
Type the exact size from your ruler, and make sure it's correct.
-
Choose between MERV 8, 11, or 13.
-
Select a pack; The price usually drops per unit, so order in bulk for the most cost-effective option.
-
Checkout with flat-rate shipping across the US and Canada.
Order custom size furnace filters online in Canada and you'll receive your package in record time. Shipping is fast, reliable, and inexpensive.

Where Can I Find Discount Furnace Filters?
Usually, custom size air filters can be expensive as they're made to match your device perfectly. However, knowing where to find the best deals and discounts will help you enjoy maximum airflow and extend the life of your HVAC motor inexpensively.
The trick is to know where to find the best, premium-quality discount furnace filters.
Order top-notch custom size furnace filters in Canada from United Filter and get the best value on the market. Better yet, buy in bulk to keep a spare on hand in case you need it in the future.
Custom Size Furnace Filters and the Most Common Mistakes
These are some of the most common mistakes we see all the time when ordering custom size HVAC filters.
-
Gaps on the side: Always make sure you're ordering the correct custom size furnace filter online. The wrong depth can also make the filter rattle or prevent the door from properly closing.
-
Sudden whistle: This usually happens due to a collapsed pleat from high static pressure. We recommend moving down one MERV tier or installing a deeper frame.
-
Static shocks at vents: When the filter is overdue or the humidity is low, you might notice static shocks. It's best to run a humidifier and swap pads.
If you have any doubts, please reach out to us at (905) 403-0160 or leave a message via the contact us page. You can also check out our comprehensive blog section to learn more about ordering custom size furnace filters, how they work, MERV ratings, and more.
Custom Size Furnace Filters in Canada: FAQ
What is the difference between nominal and actual size?
In short, the nominal size is the rounded measurement that's printed on the filter label, like 16x25x1. The actual size is the precise dimension of the filter, which is typically smaller.
How do I know if I need a custom size furnace filter?
If the current filter isn't sliding in smoothly, bends, or leaves gaps, you might need a custom size. In most cases, older systems and remodelled spaces require non-standard sizes.
How often should I replace a custom size furnace filter?
For a 1-inch filter, it's best to schedule replacements every 60 to 90 days. For 4-to 5-inch, you can extend the timeframe to every 6 to 12 months. However, it all depends on the air quality in your home, whether you have pets and the local conditions.

Order Custom Size Filters Now
Measure your furnace filter once and breathe easier all year round. The best custom size filters will give your system the tight seal it needs, prevent dust from crossing over, and maintain smooth (and consistent) airflow.
Just search our shop for custom size filters. Your blower and your lungs will thank you! Order premium custom size furnace filters for cheap from United Filter today!