Filter King is a US-based manufacturer of HVAC and furnace air filters founded in Miami, Florida. The company makes UL-certified filters in MERV 8, 11, and 13 ratings, plus activated carbon options, in standard and fully custom sizes for residential and commercial use.
Filter King holds a 4.6-star rating from 5,243 Google reviews and a 4.5-star rating from 4,314 Amazon reviews. Wirecutter named Filter King MERV 13 a runner-up for best air filter, describing it as ‘another capable filter that won’t constrict airflow.’ Four US manufacturing facilities in Miami, Las Vegas, Dallas, and Bethlehem, PA enable same-day shipping for standard sizes and 24-hour turnaround for custom orders.
This review covers what Filter King sells, how MERV ratings work, how to install a furnace filter correctly, how Filter King compares to Filterbuy, and whether the brand is worth buying for households focused on indoor air quality.
What Is Filter King?
Filter King is a leading US manufacturer of HVAC and furnace air filters offering both standard and custom sizes for residential, commercial, and industrial applications across the United States. Founded in Miami, Florida as a family-owned business, the company now operates four manufacturing and distribution facilities across three states. Filter King serves 10,000-plus homeowners and commercial clients including Ritz Carlton, Conrad Hotels, and Miami-Dade County.
Here’s the thing — Filter King isn’t a middleman. The company manufactures every filter in-house across 200,000-plus square feet (18,580 sq m) of operational space with 125-plus employees. In Q2 2025, Filter King produced more filters than any previous quarter in its nine-year history. That kind of growth doesn’t happen without a solid product.
All filters carry UL certification and are manufactured domestically. The brand offers MERV ratings of 8, 11, and 13, plus activated carbon options, in thicknesses of 0.5, 1, 2, 4, and 5 inches. Whatever size an HVAC system needs, Filter King almost certainly has it.
Who Makes Filter King Filters?
Filter King LLC is a family-owned American manufacturer founded by Rick Hoskins in Miami, Florida, now employing 125-plus workers across four US facilities totaling 200,000-plus square feet (18,580 sq m) of operational space. The company’s rapid expansion includes a Las Vegas facility opened February 2025 and a Bethlehem, Pennsylvania location opened July 2025. The 61,600 sq ft Bethlehem site specifically serves the Northeast US market.
All filters carry UL certification. The company produces over 3,800 distinct filter sizes. Hoskins has stated the goal is ‘to make best in class air filters at competitive prices, achieve rapid delivery to the customer, and to accommodate any size filter needed.’ Based on the company’s growth trajectory, that vision is executing.
What Types of Filters Does Filter King Sell?
Filter King sells MERV 8, MERV 11, and MERV 13 filters plus activated carbon options in thicknesses from 0.5 to 5 inches, covering both standard and fully custom dimensions up to over 3,800 distinct sizes. MERV 8 captures everyday dust, pollen, and lint. MERV 11 adds pet dander and mold spore capture. MERV 13 filters bacteria, smoke, and microscopic allergens as small as 0.3 microns.
Custom orders ship within 24 hours. Standard sizes include popular options like 16x20x1, 20x25x1, and 16x25x4 inches. And here’s the part most people miss — Filter King fills specialty non-standard sizes that most competitors simply don’t carry. If you’ve ever struggled to find the right filter size, Filter King is worth checking.
How Does Filter King Work?
Filter King uses electrostatically charged pleated media that physically traps airborne particles as air moves through the HVAC return duct — with higher MERV ratings using denser media and tighter pleat spacing to capture progressively smaller particles. Air is pulled from the room through the filter and into the blower system. The pleated media presents maximum surface area for particle capture while maintaining sufficient airflow through the system.
In fact, the MERV system is more precise than most people realize. MERV stands for Minimum Efficiency Reporting Value — a 1-16 scale measuring what percentage of particles a filter captures. MERV 8 captures particles 3-10 microns in size (dust, pollen, lint). MERV 13 captures particles as small as 0.3 microns (bacteria, smoke, microscopic allergens). Higher MERV ratings use denser media, which creates slightly more airflow resistance.
Filter King filters are compatible with all major HVAC brands including Carrier, Lennox, Trane, Honeywell, Goodman, and Bryant. The company covers both standard return-duct installations and blower-slot configurations. If your HVAC system takes a filter, Filter King almost certainly makes one that fits.
What Is a MERV Rating and Which Filter King Rating Is Right?
MERV rating measures what percentage of particles a filter captures — MERV 8 handles everyday dust and pollen, MERV 11 adds pet dander and mold, and MERV 13 captures bacteria and smoke for maximum indoor air quality protection. Wirecutter named Filter King’s MERV 13 a runner-up for best air filter, describing it as ‘another capable filter that won’t constrict airflow.’ The right choice depends on household needs and local air conditions.
MERV Rating Guide:
| MERV Rating | Captures | Best For |
|---|---|---|
| MERV 8 | Dust, pollen, lint (3-10 microns) | Basic homes, no pets |
| MERV 11 | Pet dander, mold spores | Pet owners, mild allergies |
| MERV 13 | Bacteria, smoke, 0.3-micron particles | Allergy sufferers, wildfire areas |
| Carbon | Odors and VOCs | Homes with odor concerns |
How Often Should You Change a Filter King Filter?
For most homes with a 1-inch filter, changing the Filter King filter every 60-90 days is the reliable baseline — but pets, allergies, filter thickness, and local air quality can shift that window significantly in either direction. Homes in wildfire regions or high-pollen areas may need changes every 30-45 days. Thicker 4-inch filters last considerably longer than 1-inch filters at the same MERV rating.
Filter King offers an auto-delivery subscription that ships replacement filters on a pre-set schedule. Subscribers save 5% per order. The service ensures filters arrive on time without requiring manual reordering. For a busy household, it’s the simplest way to stay on schedule and maintain air quality without thinking about it.
What Are the Benefits of Filter King?
Filter King combines USA manufacturing, custom sizing, UL certification, fast delivery to 80% of US addresses within 2 business days, and a 30-day money-back guarantee — a combination few domestic filter brands match at this price point. Four manufacturing facilities enable same-day shipping for standard sizes and 24-hour turnaround for custom orders. The direct-to-consumer model eliminates retail markup.
Here’s what that four-facility footprint actually means. The Bethlehem, PA location alone sits within a seven-hour drive of 40% of the US population. Combined with facilities in Miami, Las Vegas, and Dallas, Filter King achieves coast-to-coast rapid delivery. Competitive pricing, domestic manufacturing, and the ability to fill any custom size define the brand’s core value proposition.
Filter King Key Benefits:
- USA-manufactured across 4 facilities
- UL-certified across all MERV ratings
- Custom sizes in any dimension (ships in 24 hours)
- 2-day delivery to 80% of US addresses
- 30-day money-back guarantee
- Auto-delivery subscription saves 5%
Does Filter King Make Filters in the USA?
Yes. Filter King manufactures all filters in the USA across four facilities in Miami, Las Vegas, Dallas, and Bethlehem totaling 200,000-plus square feet (18,580 sq m), with over 3,800 distinct filter sizes produced domestically. The company produced its highest-volume quarter in nine years during Q2 2025. Domestic manufacturing enables shorter lead times, consistent quality oversight, and faster delivery than import-dependent competitors.
USA manufacturing also allows Filter King to fulfill custom orders within 24 hours. The company carries MERV 8, 11, and 13 ratings, all manufactured to UL-certified specifications. Filterbuy and other domestic competitors also manufacture in the US, but Filter King’s four-facility geographic distribution gives it a real delivery speed advantage.
Does Filter King Offer Custom Filter Sizes?
Yes. Filter King produces custom HVAC filters to any specified dimension within 24 hours — the company manufactured over 3,800 different filter sizes in a single month and ships custom orders with the same fast delivery as standard sizes. Customers specify length, width, and depth in inches. Filter King cuts the filter to those dimensions and ships it directly.
Standard sizes available include filters from narrow dimensions under 10 inches wide to large filters over 30 inches wide, across 1, 2, and 4-inch thicknesses. The brand serves both homeowners with non-standard ductwork and commercial contractors needing precision-cut filters for large-format HVAC systems. If a size exists, Filter King almost certainly makes it.
What Do Filter King Reviews Say?
Filter King holds a 4.6-star rating from 5,243 Google reviews and a 4.5-star rating from 4,314 Amazon reviews; Wirecutter named Filter King MERV 13 a runner-up for best air filter with strong filtration and minimal HVAC-system strain. Most reviews highlight fast shipping, accurate sizing, and responsive customer service. Expert coverage focuses on performance and value versus premium-tier brands.
Wirecutter describes Filter King MERV 13 as ‘another capable filter that won’t constrict airflow’ — the kind of language that means the filter does its job without making the HVAC system work harder than it needs to. Commercial clients including Ritz Carlton and Conrad Hotels also recognize Filter King for consistent quality and reliable delivery at scale.
Review Scores:
| Platform | Rating | Reviews |
|---|---|---|
| 4.6 stars | 5,243 | |
| Amazon | 4.5 stars | 4,314 |
| Wirecutter | Runner-up | MERV 13 Best Filters |
What Are the Positive Experiences?
Positive Filter King reviews consistently praise fast shipping, precise filter fit, hard-to-find size availability, and outstanding customer service as the brand’s defining strengths. One verified buyer called customer service ‘truly outstanding.’ Another praised Filter King for ‘fast service for a filter size that is hard to find.’ Commercial HVAC partners describe the company as professional with orders that are ‘always correct and deliveries on time.’
So what does that mean in practice? Several B2B clients highlight short lead times, competitive pricing, and job-site delivery as key advantages. One HVAC contractor partner wrote: ‘The filters are of high quality and I am very happy with the service.’ The consistent theme across residential and commercial reviews is that Filter King executes reliably — the filters fit, they arrive fast, and the service resolves problems quickly.
What Are the Common Complaints?
The most common Filter King complaint involves reports of MERV 11 filters clogging prematurely — some users report 6-week lifespans instead of the expected 90 days — alongside claims of batch-to-batch inconsistency in frame durability and media density. These reports come primarily from users comparing Filter King against premium brands like Filterbuy. Filter King’s UL certification covers the stated filter specifications, but real-world performance can vary by batch and household conditions.
A competitor analysis notes Filter King ‘sources filters through various manufacturing channels, which can create inconsistencies in frame durability and media density between batches.’ The good news? The 30-day money-back guarantee covers any filter that underperforms. If a filter clogs in 6 weeks, a replacement request within 30 days qualifies for a full refund.
How Do You Install a Filter King Filter?
Filter King installation takes under 5 minutes: locate the filter slot, remove the old filter, confirm the new filter’s size and airflow direction arrow, and slide it into place with the arrow pointing toward the blower motor. No tools are required. The filter size is printed on the cardboard frame in three numbers (length x width x thickness — example: 20x25x1 inches / 50.8×63.5×2.5 cm).
If the size markings on the old filter are faded, measure the filter slot with a tape measure. Measure length, width, and depth in inches and round to the nearest whole number. This gives the nominal size — the standard measurement used by Filter King and all other filter manufacturers. Think of it this way: the slot measurement IS the size to order.
Installation Steps:
- Locate the filter slot near the return air duct or furnace blower
- Remove the old filter and note its size printed on the frame
- Check the airflow arrow on the new Filter King filter
- Slide the new filter in with the arrow pointing toward the blower
- Close the access panel and reset your replacement reminder
Where Is the Furnace Filter Located?
The furnace filter sits between the return air duct and the blower motor — typically in a slot inside the furnace near the blower compartment, at a filter rack where the return duct meets the furnace, or behind a large return air vent on a wall or ceiling. Most homeowners find the filter by following the largest air duct back to the furnace or air handler unit.
In homes with horizontal HVAC units installed in attics or crawl spaces, the filter is located where the return duct connects to the air handler — usually in a side-access panel. Some older homes route the return air duct to a large wall vent in a hallway or central room, with the filter installed directly behind the vent cover. When in doubt, follow the large duct.
Which Way Does the Arrow Go on a Filter King Filter?
The arrow on the Filter King filter points in the direction of airflow — toward the furnace blower motor and away from the return duct — and installing the filter backward reduces filtration efficiency and pushes contaminants into the HVAC system. Air flows from the room through the return duct, through the filter media, and into the blower. The arrow marks this path exactly.
Here’s why getting this right matters. Installing the filter backward forces air through the wrong side of the pleated media. This significantly reduces particle capture and can allow unfiltered air to bypass the media along the filter frame edges. Correct installation takes 5 seconds to verify — check the arrow before sliding the filter in, every single time.
How Much Do Filter King Filters Cost?
Filter King positions its filters at a competitive mid-range price point below premium brands like Filterbuy — standard 1-inch filters start under $10 and the auto-delivery subscription saves 5% on every order for subscribers who set a recurring delivery schedule. All orders qualify for fast shipping, and exact pricing varies by MERV rating, size, and thickness. Thicker and higher-MERV filters cost more than basic 1-inch MERV 8 options.
The 30-day money-back guarantee applies to all stocked filters. Customers who order the wrong size or rating can return it within 30 days for a full refund with no questions asked. Custom filters are made to order — check current return terms for custom orders at filterking.com before purchasing a specialty size.
Is Filter King Worth the Price?
Yes. Filter King delivers UL-certified, USA-made HVAC filtration with same-day shipping, custom size capability, and a 30-day money-back guarantee at competitive pricing — making it worth the cost for most households replacing filters on schedule. The auto-delivery subscription locks in a 5% discount and removes the hassle of manual reordering. For households changing filters every 60-90 days, the annual cost stays manageable across all MERV ratings.
The brand’s Wirecutter runner-up status and 4.6-star Google average confirm consistent satisfaction at scale. For households that want more reliability than budget no-name brands but don’t want to pay premium Filterbuy prices, Filter King occupies exactly the right price-performance position. And the money-back guarantee means the first order is risk-free.
Filter King vs Filterbuy: Which Is Better?
Filter King offers lower upfront pricing, broader custom sizing, and wider size availability compared to Filterbuy, while Filterbuy claims tighter manufacturing consistency and more reliable real-world MERV performance — making the right choice depend on what the buyer values most. Both brands manufacture in the USA and offer MERV 8, 11, and 13 options.
By comparison, reports suggest Filter King MERV 11 can underperform Filterbuy MERV 8 in some households, with some users experiencing premature clogging. Filterbuy attributes this to pleat density and media weight differences. Filter King counters with broader custom sizing, more aggressive pricing, and four-facility coast-to-coast manufacturing. For most standard-size needs, either brand works well — Filter King’s real advantage is price and custom options.
Should You Try Filter King at Eat Proteins?
Filter King is a Wirecutter-recognized, UL-certified HVAC filter brand with 4.6 stars across 5,000-plus reviews, USA manufacturing across four facilities, same-day shipping for standard sizes, 24-hour custom orders, and a 30-day money-back guarantee — one of the strongest all-around value propositions in the residential air filter market. No competing domestic brand at this price point offers the same combination of custom sizing speed and delivery coverage.
Our team at Eat Proteins recommends Filter King MERV 13 for health-conscious households concerned about indoor air quality, wildfire smoke, and respiratory allergens. MERV 13 filtration removes bacteria, smoke, and microscopic allergens as small as 0.3 microns. Changing filters on schedule is one of the most impactful low-cost investments in long-term respiratory health. Don’t skip it.
Filter King is available at filterking.com and Amazon. Use the auto-delivery subscription to save 5% and stay on your replacement schedule automatically. Custom sizes ship in 24 hours. Start with MERV 13 and feel the difference in your home’s air quality today.