Furnace filters · MERV 8 vs 11 vs 13 · Ontario winter
Furnace filter MERV for Ontario winters: MERV 8 vs 11 vs 13
Your gas furnace pulls every bit of household air through one filter, all winter long. For most Ontario homes with a standard 1-inch filter slot, MERV 11 is the sweet spot: it catches more fine dust and pet dander than MERV 8 without choking airflow. MERV 8 is the safe choice for older furnaces, and MERV 13 is only worth it when your furnace can handle it. Below: an original MERV comparison, how often to change it, the over-filtering mistake, and in-stock picks on Amazon.ca, Made in Canada first.
Top pick for most Ontario furnaces: Filtrete MERV 11 16x25x1 4-pack
Why this pick: MERV 11 is the best balance of particle capture and airflow for a typical 1-inch furnace slot, and this 4-pack covers a full heating season if you change it every 2 to 3 months. It is one of the most-reviewed 16x25x1 filters on Amazon.ca, ships from and is sold by Amazon.ca, and was in stock when we checked. It is imported; our Made-in-Canada pick is below.
Check price on Amazon.ca
$56.98 CAD · about $14.25 per filter
4.7 ★ · 24,463 reviews
In stock · ships from and sold by Amazon.ca (checked Oct 30)
Buy Canadian first: the Filtrete MERV 8 4-pack is labelled made in Canada on Amazon.ca, and it is also shipped and sold by Amazon.ca. Made in Canada ≠ Canadian brand: Filtrete belongs to 3M, an American company. For a Canadian-made MERV 11 in bulk, see the 12-pack shipped by a Canadian seller.
Check the size printed on your old filter before you order. CAD prices are approximate and change often.
MERV 8 vs 11 vs 13 for a typical Ontario furnace
This table assumes a forced-air gas furnace with a standard 1-inch filter slot, which is what most Ontario houses and townhouses have. Thicker 4- or 5-inch media cabinets handle higher MERV with less airflow loss.
MERV 8, MERV 11 and MERV 13 furnace filters compared for particle capture, airflow, change interval and fit for Ontario homes
| Question |
MERV 8 |
MERV 11 |
MERV 13 |
| What it catches |
Household dust, lint, pollen and larger particles. Protects the furnace blower and coil. |
Everything MERV 8 does, plus more fine dust and pet dander. |
More of the finest particles, including a larger share of smoke-sized particles. |
| Airflow in a 1-inch slot |
Easiest on airflow. Safe for almost any furnace. |
Fine for most furnaces from the last 20 years or so. |
Can restrict airflow on older furnaces or tight return ducts. Check first. |
| Winter change interval |
Check monthly. Change every 2 to 3 months. |
Check monthly. Change every 2 to 3 months, sooner with pets. |
Check monthly. It loads up faster, so plan on every 1 to 2 months. |
| Best fit |
Older furnaces, a quiet household, or anyone who changes filters less often. |
Most Ontario homes, including pets, kids and renovation dust. |
Homes that get regular wildfire smoke days, with a furnace that is rated for it. |
| Watch-outs |
Lets more fine dust through than MERV 11. |
Costs a little more per filter than MERV 8. |
A clogged MERV 13 can make the furnace work harder. Ask an HVAC technician if unsure. |
| Our pick on Amazon.ca |
 Filtrete MERV 8 4-pack (Made in Canada) $46.13 · 4.6 ★ · 294 reviews |
Filtrete MERV 11 4-pack $56.98 · 4.7 ★ · 24,463 reviews |
 MERV 13 6-pack (third-party seller) $74.99 · 4.6 ★ · 1,507 reviews |
If you are not sure, start with MERV 11, check it after a month, and watch the airflow at your vents. If airflow drops or the filter bows, go back to MERV 8 and talk to an HVAC technician.
16x25x1 furnace filters compared: Made in Canada first, then imported
Price per filter is the pack price divided by the number of filters. All sizes are nominal; the actual filter is slightly smaller, which is normal.
16x25x1 furnace filters: origin label, MERV, pack size, CAD price, price per filter, shipping and Amazon.ca rating
| Filter |
Label |
MERV |
Pack |
Price (CAD) |
Per filter |
Ships from / sold by |
Amazon.ca rating |
| Filtrete MPR 700 16x25x1 |
Made in Canada |
8 |
4 |
$46.13 |
~$11.53 |
Amazon.ca · in stock |
4.6 ★ · 294 reviews |
 FurnaceFilters.Ca 16x25x1 case of 12 |
Made in Canada |
11 |
12 |
$89.99 |
~$7.50 |
Shipped and sold by the seller, not Amazon |
4.7 ★ · 1,172 reviews |
| Filtrete MPR 1000 16x25x1 |
Imported |
11 |
4 |
$56.98 |
~$14.25 |
Amazon.ca · in stock |
4.7 ★ · 24,463 reviews |
 Amazon Basics 16x25x1 MERV 11 |
Imported |
11 |
6 |
$59.99 |
~$10.00 |
Amazon.ca · in stock |
4.4 ★ · 5,814 reviews |
| 16x25x1 MERV 13 pleated 6-pack |
Imported |
13 |
6 |
$74.99 |
~$12.50 |
Ships from Amazon · sold by a third-party seller |
4.6 ★ · 1,507 reviews |
Made in Canada
We lead with filters made in Canada. We label them honestly: Made in Canada describes where the filter was made, not who owns the brand.
Made in Canada
Ships from and sold by Amazon.ca
Filtrete MPR 700 MERV 8, 16x25x1, 4-pack
Labelled made in Canada on its Amazon.ca listing, and shipped and sold by Amazon.ca. MERV 8 is the easiest on airflow, so it is the safe pick for an older furnace that runs hard all winter. Honest label: Filtrete is a 3M brand and 3M is American, so this is Made in Canada, not a Canadian brand.
- Rating: MERV 8 (MPR 700)
- Size: 16x25x1 nominal (about 15.7 x 24.6 x 0.8 in actual)
- Rated for up to 3 months per filter
Check price on Amazon.ca
Made in Canada
Shipped by the seller · not Amazon
FurnaceFilters.Ca MERV 11, 16x25x1, case of 12
A Canadian-made MERV 11 case of 12 from a Canadian filter seller, and the lowest cost per filter on this page. It is shipped and sold by the seller, not by Amazon, so expect a few extra days for delivery. A good stock-up buy if you change monthly or have more than one furnace.
- Rating: MERV 11
- Size: 16x25x1 nominal
- 12 filters: a year of monthly changes
Check price on Amazon.ca
Imported alternatives
Top pick
Imported
Ships from and sold by Amazon.ca
Filtrete MPR 1000 MERV 11, 16x25x1, 4-pack
Our top pick for most Ontario furnaces. MERV 11 catches more fine dust and pet dander than MERV 8 while staying gentle enough on airflow for most 1-inch slots. Tens of thousands of Amazon.ca reviews and shipped and sold by Amazon.ca.
- Rating: MERV 11 (MPR 1000)
- Size: 16x25x1 nominal (about 15.7 x 24.7 x 0.8 in actual)
- Rated for up to 3 months per filter
Check price on Amazon.ca
Imported alternative
Ships from and sold by Amazon.ca
Amazon Basics MERV 11, 16x25x1, 6-pack
The value MERV 11: about $10 a filter, shipped and sold by Amazon.ca. Six filters let you change monthly through the coldest months, or during renovation and shedding season, without paying Filtrete prices.
- Rating: MERV 11
- Size: 16x25x1 nominal (about 15.75 x 24.75 x 0.75 in actual)
- Electrostatic pleated media
Check price on Amazon.ca
Imported
Ships from Amazon · third-party seller
MERV 13 pleated 16x25x1, 6-pack
For homes that see regular wildfire smoke days and a furnace that can handle a denser 1-inch filter. It ships from Amazon but is sold by a third-party seller, not Amazon.ca, and we could not find a MERV 13 that Amazon.ca sells itself. Check your furnace manual or ask an HVAC technician before going above MERV 11.
- Rating: MERV 13
- Size: 16x25x1 nominal
- Change more often: every 1 to 2 months
Check price on Amazon.ca
Have a 16x20x1 slot instead?
16x20x1 is the other common 1-inch size in Ontario homes. The Filtrete MERV 11 16x20x1 2-pack is shipped and sold by Amazon.ca (imported). It costs more per filter (about $23.46) because it is a 2-pack, so buy two packs for a full winter.
Filtrete MERV 11 16x20x1 2-pack · imported
Check price on Amazon.ca
~$46.91 CAD
4.6 ★ · 50,036 reviews
In stock · ships from and sold by Amazon.ca (checked Oct 30)
How often to change a furnace filter in an Ontario winter
- Check monthly from the first cold snap (usually October) until you turn the heat off in spring. Pull the filter and hold it up to a light. If you cannot see light through it, change it.
- Every 2 to 3 months is typical for MERV 8 or 11 in a home without pets.
- Every 1 to 2 months with pets, a busy household, renovation or drywall dust, or after smoky days, and for MERV 13.
- Write the date on the frame when you put a new one in.
- If you run the furnace fan on "On" all the time instead of "Auto", the filter loads up faster.
Don't over-filter: the MERV 13 mistake
Higher MERV is not automatically better for your furnace. A denser 1-inch filter makes the blower work harder to pull air through it, and a clogged one can cut airflow further.
- Signs of too much restriction: noticeably weaker airflow at the vents, a whistle at the filter slot, a filter that bows or gets sucked in, or rooms that take longer to warm up.
- Check first: your furnace manual or the label inside the furnace door may list a maximum filter rating or a recommended filter type.
- A better upgrade path: if you want MERV 13 all the time, ask an HVAC technician about a 4- or 5-inch media filter cabinet, which has much more surface area.
- Never run without a filter, even for a day. Dust builds up on the blower and coil.
Sizing and installing it the right way
- Read the old filter. The nominal size (for example 16x25x1) is printed on the frame. Buy that size. The actual size is slightly smaller, and that is normal.
- Arrow toward the furnace. The airflow arrow on the frame points toward the blower, away from the return duct.
- No gaps. The filter should sit snugly in the slot. Air that goes around the filter is not filtered.
- Not sure? If there is no filter, no label or an odd-sized slot, ask an HVAC technician at your next furnace tune-up.
Wildfire smoke days: furnace filter plus a room purifier
A better furnace filter helps only while the fan is moving air through it, and it filters the whole house slowly. On smoke days, keep windows shut, set the furnace fan to "On" if your filter and system can handle it, and run a portable HEPA purifier in the bedroom with the door closed. See our Buy Canadian HEPA air purifier shortlist for room sizing, and the air purifier filter replacement guide for purifier filters (a different product from furnace filters). This page is general information, not medical advice.
Furnace season also dries the air
A clean MERV 11 filter keeps airflow steady, but forced-air heat still strips moisture from upstairs rooms. If a $15 hygrometer reads under 30% RH, add a portable humidifier. Hard tap water? Prefer evaporative (Vornado Evap40). Want quiet app control? Prefer ultrasonic (Levoit Classic 300S).
Check price on Amazon.ca
~$132.29 CAD
4.3 ★ · 3,995 reviews
In stock · ships from and sold by Amazon.ca (checked Oct 30)
Winter humidifier shortlist
Ontario condo humidifier guide
Questions people ask
What MERV rating should I use in my furnace in Ontario?
For most Ontario gas furnaces with a standard 1-inch filter slot, MERV 8 to MERV 11 is the practical range. MERV 8 is the safe default for older furnaces. MERV 11 catches more fine dust and pet dander and suits most newer furnaces. Go to MERV 13 only if your furnace manual or HVAC technician says the system can handle it.
Is MERV 13 too much for a 1-inch furnace filter?
It can be. A 1-inch MERV 13 filter is denser and can restrict airflow on some furnaces, especially older ones or systems with undersized return ducts. Watch for weaker airflow at the vents, a whistle at the filter slot or a filter that bows. If you see any of these, drop back to MERV 11 and ask an HVAC technician.
How often should I change my furnace filter in winter?
Check it every month while the heat is on and replace it when it looks grey or clogged. Many 1-inch pleated filters are rated for up to 3 months, but pets, renovation dust, a busy household or smoky outdoor air can mean changing it every 1 to 2 months.
How do I find my furnace filter size?
Read the size printed on the frame of the filter you have now, for example 16x25x1. That is the nominal size; the actual filter is usually slightly smaller, and that is normal. 16x25x1 and 16x20x1 are common in Ontario homes. If there is no filter or no label, measure the slot and ask an HVAC technician before you buy.
Is Filtrete a Canadian brand?
No. Filtrete is a 3M brand, and 3M is an American company. The Filtrete MERV 8 4-pack we list is labelled made in Canada on its Amazon.ca listing, so we give it a Made in Canada badge only, not a Canadian brand badge. The Filtrete MERV 11 packs we list are imported.
Will a better furnace filter help on wildfire smoke days?
A higher-MERV filter catches more fine particles when the furnace fan is running, but it does not clean the air in a closed bedroom on its own. On smoke days, keep windows shut, run the furnace fan if your filter and system allow it, and use a portable HEPA purifier in the room where you sleep. This is general information, not medical advice.
CAD prices, Amazon star ratings and review counts are approximate (checked Oct 30, 2026 ET). Confirm the live Amazon.ca listing before you buy.
