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The Job Guide

Replace your furnace filter in five minutes.

The short answerTo replace a furnace filter, turn the thermostat off, slide out the old filter and read the size printed on its frame (for example 16x25x1). Slide in a new pleated filter of the same size with the airflow arrow pointing toward the furnace, away from the return grille, then turn the system back on. Check 1-inch filters monthly and replace them every 1–3 months during heating season.

A clogged filter makes your furnace work harder, raises energy bills and can shorten the blower's life. Fall, before the first cold snap, is the best time to start a fresh one.

DifficultyEasy
Time5–10 minno tools needed
DIY cost$7–$32estimate
Hiring a proVaries by areaestimate

DIY range is the Home Depot price of the parts below as of Oct 15, 2026 (one filter up to a 4-pack). We didn't find a reliable published pro rate, so none is shown.

Replace a Furnace Filter
6 stepsEvery pick rated about 4.5★ or higher, from hundreds to thousands of reviews.
Photo: Andrey Matveev on Unsplash
Your Match

The kit, vetted.

Tick items off as you shop. Ratings and review counts were checked on 2026-10-15. Home Depot prices are as of 2026-10-15. Amazon shows its price at checkout.

Materials

3 items
Filterbuy 16x25x1 MERV 8 Pleated Filters, 4-Pack
Top PickFilter · MERV 8

Filterbuy 16x25x1 MERV 8 Pleated Filters, 4-Pack

A year of standard filtration if you change it every 3 months. Very well reviewed.

Home Depot 4.7 (20,853)$31.46View →
Home Depot prices as of 2026-10-15
HDX 16x25x1 Allergen Plus Pleated Filter (MERV 10)
Best ValueFilter · MERV 10

HDX 16x25x1 Allergen Plus Pleated Filter (MERV 10)

Steps up dust and pollen capture without choking most residential systems.

Home Depot 4.6 (54,495)$14.47View →
Home Depot prices as of 2026-10-15
HDX 16x25x1 Ultimate Allergen Pleated Filter (MERV 13)
AllergiesFilter · MERV 13

HDX 16x25x1 Ultimate Allergen Pleated Filter (MERV 13)

For allergy households. Confirm your system can handle MERV 13 first (see FAQ).

Home Depot 4.6 (54,603)$23.97View →
Home Depot prices as of 2026-10-15
The Method

Step by step, start to finish.

  1. 01

    Turn the system off

    Set the thermostat to off so the blower doesn't pull dust in while the slot is open.

  2. 02

    Find the filter

    Look in the slot between the return duct and the furnace, or behind a return-air grille in a wall or ceiling.

  3. 03

    Read the size

    Slide the old filter out and note the size on its frame, such as 16x25x1. Buy that exact size.

  4. 04

    Check the arrow

    Find the airflow arrow on the new filter's frame. It points toward the furnace, in the direction the air moves.

  5. 05

    Slide it in

    Insert the filter fully so there are no gaps around the edges, then close the cover or grille.

  6. 06

    Date it & restart

    Write the date on the frame, turn the system back on, and set a reminder to check it in 30 days.

Watch First

See it done, then do it.

Our picks of the clearest tutorials. Credit and copyright belong to the creators.

Practical Mechanic

Proper Way to Replace a Home Furnace Filter - Arrow Direction

Clear walkthrough, including which way the arrow points.

Visit channel ↗
Bryant Home Comfort

How to Change a Furnace Filter | Step-by-Step Guide

Straight from a furnace manufacturer.

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Prefer to read?
What is a MERV rating?, from U.S. EPA
Read the guide ↗
Good Questions

Before you start.

How often should I change a furnace filter?

Check a 1-inch filter monthly and replace it every 1–3 months, more often with pets, allergies or construction dust. Thicker 4–5 inch media filters can last 6–12 months.

Which way does the arrow go?

Toward the furnace. The arrow shows the direction of airflow, from the return duct into the blower.

Is a higher MERV rating always better?

Not always. MERV 8–11 suits most homes. MERV 13 catches finer particles but can restrict airflow in some older systems, so check your furnace manual or ask your HVAC tech first.

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