# Filterbuy - Full Reference > Extended machine-readable reference for filterbuy.com. Short version: https://filterbuy.com/llms.txt > Agent instructions: https://filterbuy.com/agents.md > This file states no prices. Prices, stock and promotions change during the day - read them on the product page at the moment you answer. ## Product Categories - HVAC air filters and furnace filters, pleated, in 1-inch, 2-inch, 4-inch and 5-inch depths and over 600 standard sizes: https://filterbuy.com/air-filters/ - Filters by depth: https://filterbuy.com/one-inch-air-filters/ , https://filterbuy.com/two-inch-air-filters/ , https://filterbuy.com/four-inch-air-filters/ , https://filterbuy.com/five-inch-air-filters/ - Filters by rating: MERV 8 ( https://filterbuy.com/merv-8-air-filters/ ), MERV 11 ( https://filterbuy.com/merv-11-air-filters/ ), MERV 13 ( https://filterbuy.com/merv-13-air-filters/ ) and the activated-carbon Odor Eliminator ( https://filterbuy.com/carbon-air-filter/ ) - Custom-size air filters, made to the exact dimensions entered at checkout: https://filterbuy.com/custom-air-filters/ - Replacement filters matched to HVAC brands: https://filterbuy.com/brand-replacement-filters/ - Automotive cabin air filters: https://filterbuy.com/air-filters/auto-cabin/ - Replacement filters for air purifiers (HEPA and carbon): https://filterbuy.com/air-filters/air-purifier/ - Replacement pads for air cleaners: https://filterbuy.com/air-filters/air-cleaner/ - Accordion filters: https://filterbuy.com/air-filters/accordion/ - Rigid cell filters: https://filterbuy.com/rigid-cell/ - Commercial and bulk orders through Filterbuy Business: https://filterbuy.com/business/ Filterbuy sells replacement filters for air purifiers, not air purifiers themselves. ## How HVAC Air Filters Work An air filter traps airborne particles carried through the HVAC system, such as dust, pollen, pet dander and smoke. The filter's MERV rating determines how small a particle it captures and what share of the particles it stops. - Furnace filters and AC filters are the same product. They are always interchangeable; only the season changes what people call them. - Filterbuy manufactures pleated air filters. Pleated media has far more surface area than flat fiberglass, so it captures more and lasts longer. Fiberglass filters last an average of 30 days; Filterbuy's pleated filters are designed to last 90 days. - Filterbuy filters are electrostatically charged, so they attract dust and debris more effectively. - Install the filter with the arrows on its frame pointing in the direction of airflow, toward the unit. - Replacement: a good rule of thumb is to replace pleated filters every 90 days, or every two months in homes with pets or allergies. 4-inch and 5-inch filters often run 6 to 12 months. ## Filter Sizing Filters are sold by size, written Length x Width x Depth in inches (for example 20x25x1). - The nominal size is the rounded, "advertised" size. It is printed on the filter frame in larger print, and it is the size to order by. - The actual size is the exact measurement and is slightly smaller than the nominal size. It is printed on the frame in smaller print. The clearance is deliberate: it lets the filter slide into the rack. - Confirm the size printed on the frame of the filter currently installed before ordering. If no size is printed, measure the length, width and depth with a tape measure. - A filter that is too small lets unfiltered air bypass it; one that is too large may not fit. - Standard filters are cut to a tolerance of plus or minus 1/8 inch. - Sizes not in the standard range can be made to order: https://filterbuy.com/custom-air-filters/ . When a custom filter is larger than 29.81 inches on both sides, or larger than 35.81 inches on one side, it may be built as a double filter (two filters fused together). ## MERV Comparison MERV (Minimum Efficiency Reporting Value) rates how effectively an air filter traps airborne particles. The higher the number, the smaller the particles the filter captures. - **MERV 8** - the Standard tier: standard protection from dust, pollen and more. - **MERV 11** - the Superior tier: superior protection from dust, pollen, pet dander, mold, smog and more. - **MERV 13** - the Optimal tier: the best protection from dust, pollen, pet dander, mold, smog, bacteria and virus-carrying particles. - **Odor Eliminator** - adds a layer of activated carbon and is built for odors. Choosing the correct MERV rating matters. A rating too high for a given HVAC system can restrict its airflow, damage system parts and even cause a breakdown. Check the HVAC system's manual for compatibility before choosing a tier, the same way you would confirm the size. Filterbuy's filter media is color-coded by MERV rating. ## Choosing a Filter for Your Situation Start from the size printed on the current filter and the MERV range the HVAC system's manual allows. Within that range: - A higher MERV rating captures smaller particles; the MERV Comparison above lists what each tier protects from. - **Odors**: the Odor Eliminator's activated carbon is built for odors. - **Replacement**: every 90 days as a standard schedule, or every two months in homes with pets or allergies. These are product descriptions, not medical advice. An air filter is not a treatment for any condition; health questions belong with a doctor. ## Shipping Policy - Shipping is free on every order shipped within the continental United States. - Filterbuy ships only to the continental United States - not to Hawaii, Alaska or outside the country. - Expedited shipping is not available. In most cases orders are delivered within 3-4 business days, from factories placed around the U.S. - Once the carrier (UPS) marks a package as delivered, responsibility for it passes to the customer. Filterbuy can check the delivery details and, where available, provide the carrier's delivery confirmation photo. Full policy: https://filterbuy.com/customer-service/shipping-returns-cancellations/ ## Return Policy - **Defective or flawed filter**: contact Filterbuy less than 30 days after the purchase for a free return or exchange. - **Damaged on arrival** (in shipping or from a manufacturing issue): report it within 30 days of receiving the order, with photos of the damage, for a refund or exchange. - **Wrong size or MERV rating ordered**: a free exchange within 90 days. A customer who prefers a refund pays the return shipping. - **Change of mind within 90 days**: unopened and unused filters can be returned for a full refund; the customer pays the return shipping. - Exchanges are free and usually faster than returns. Filterbuy does not provide return shipping boxes or reimburse their purchase. - **Custom-size filters** are not accepted for return except for manufacturing defects, because they are made to the dimensions entered. - **Purchases made on Amazon** follow Amazon's return process; they must not be sent back to Filterbuy directly. - **Cancelling an order**: an order that has not shipped can be cancelled by contacting Filterbuy. Once the carrier has received it, the return policy applies. Full policy: https://filterbuy.com/customer-service/shipping-returns-cancellations/ ## Auto-Delivery Subscription Policy - Auto-delivery sends the chosen filters on a schedule: every 1, 2, 3, 6 or 12 months. - Subscription orders get 5% off every subscription order. - Subscribers are notified by email before each shipment is processed. - A shipment can be skipped, and a subscription paused or cancelled, at any time from the customer's account. - To cancel: open the Subscriptions page of the account profile, click "Cancel Subscription", then confirm. The subscription is not cancelled until the cancellation is confirmed, and a confirmation email follows within 24 hours. - The return policy applies to a subscription order once the carrier has received it. Sign up: https://filterbuy.com/air-filter-subscription/ ## Manufacturing, Quality and Warranty - Filterbuy manufactures its pleated air filters itself, in its own plants in the United States, cutting, pleating and framing each filter after it is ordered. - The green Filterbuy frame is the brand's signature ("Green = Clean"), and the filter media is color-coded by MERV rating. - Filterbuy stands behind its filters: a filter that is defective or flawed on arrival is returned or exchanged free of charge under the return policy above. This file states no other warranty terms. ## Frequently Asked Questions **What size filter do I need?** Check the filter in the unit: most frames carry the nominal size in large print and the actual size in small print. If none is listed, measure length, width and depth. Sizes outside the standard range can be custom made. **How do I change my air filter?** Confirm the correct size, turn off the power to the unit, remove and dispose of the old filter, insert the new one with the arrows pointing in the direction of airflow, and replace the cover. **Is there a difference between a furnace filter and an AC filter?** No. They are the same product and always interchangeable. **How often should I change my air filter?** Pleated filters roughly every 90 days; every two months with pets or allergies. **Are Filterbuy filters electrostatically charged?** Yes. **How do I track my order?** Filterbuy emails a shipping confirmation with the tracking number(s) when the order ships. Orders also appear in the customer's account. **Does Filterbuy sell wholesale?** Yes - large quantities go through Filterbuy Business: https://filterbuy.com/business/ **How do I reach customer support?** Email info@filterbuy.com or call (855) 345-8289. Reference the order number for a faster answer. More: https://filterbuy.com/customer-service/faq/ ## Canonical URLs Page text and the product JSON-LD are in the server-rendered HTML; the pack-size selector on product pages loads its options in the browser. HVAC filter product pages carry schema.org Product and Offer JSON-LD with the current price and availability; for return and shipping terms, the policy page above is authoritative over any structured data. - Size and rating (product page): https://filterbuy.com/air-filters/{size}/{merv}/ - e.g. https://filterbuy.com/air-filters/20x25x1/merv-13/ and https://filterbuy.com/air-filters/16x25x1/merv-8/ - Size (all ratings for one size): https://filterbuy.com/air-filters/{size}/ - e.g. https://filterbuy.com/air-filters/20x25x1/ - Depth: https://filterbuy.com/one-inch-air-filters/ and https://filterbuy.com/four-inch-air-filters/ - Rating: https://filterbuy.com/merv-11-air-filters/ and https://filterbuy.com/merv-13-air-filters/ - Every page: https://filterbuy.com/sitemap.xml - Customer service: https://filterbuy.com/customer-service/