How to Make a DIY Air Purifier: 3 Cheap Builds

We spend about 90 percent of our lives indoors ⁽¹⁾. That is a lot of time breathing air that often holds more dust, dander, and smoke than the air outdoors. Indoor air pollution builds up over time and can cause itchy eyes, headaches, and respiratory issues ⁽²⁾.

Commercial air purifiers work well, but they often cost a lot. The idea behind them is simple: a fan pulls air through a filter. You can copy that mechanism at home for a fraction of the price.

Your build might not look as sleek as a store unit, but the cleaning power can hold its own. Here are three ways to make your own air purifier, plus what the testing actually says about how well they work.

1. Plastic Container Air Filter

The plastic bucket purifier is a clever budget-friendly option. It takes a bit of assembly, but the materials are cheap and easy to find at any hardware store.

You can customize this build with different filters. Use basic dust filters for general cleaning or higher-rated filters for smoke and fine particles.

What You’ll Need

• Round two-gallon plastic container with a lid.
• Small portable fan (high velocity works best).
• Sandpaper.
• Power drill.
• A flexible filter.

Step-By-Step

1. Measure the fan: Check the diameter of the fan’s head. Trace this circle onto the center of the bucket’s lid.
2. Cut the lid: Carefully cut out the traced circle with a box cutter or heavy-duty knife. The fan head should sit snugly in this hole.
3. Drill intake holes: Drill 1-inch to 2-inch holes all around the sides of the bucket. These are your air intake ports.
4. Sand the edges: Smooth out the drilled holes with sandpaper to remove sharp plastic burrs.
5. Size the filter: Cut your filter fabric so the height matches the bucket’s interior height and the length covers the inner circumference.
6. Install the filter: Line the inside of the bucket with the filter, covering all the intake holes you drilled.
7. Create a cord notch: Cut a small notch in the top rim of the bucket for the fan’s power cord to exit.
8. Assemble: Place the fan into the hole in the lid, secure the lid onto the bucket, and plug it in.

2. The Wooden Air Purifier

If you dislike the look of a plastic bucket, this wood-based method is for you. It takes more handy work, but it blends in better with your home decor.

What You’ll Need

• Old wooden side table or box frame.
• Furnace filters.
• Screws.
• Drill.
• Saw.
• Air vent grate.
• Motorized fan.

Step-By-Step

1. Prep the frame: Remove three side panels of the furniture piece, leaving the bottom, top, and corner supports intact.
2. Mount the filters: Buy filters that match the size of the removed panels. Screw or frame these filters into the three open sides.
3. Install the exhaust: Cut an opening in the fourth wooden panel (or the top) and install the air vent grate. This creates an exit for clean air.
4. Manage the wiring: Drill a small hole in the wood for the fan’s power cord.
5. Mount the fan: Secure the fan inside the box, aiming it toward the exhaust vent. Seal any large gaps so airflow goes through the filters.

You can make this as simple or as fancy as you like. Some DIYers build slide-in rails for the filters, which makes them easier to swap out later.

3. HEPA DIY Air Purifier

This is the easiest and often most effective method. If you deal with allergies or asthma, this setup is a big help. A true HEPA filter traps 99.97 percent of particles as small as 0.3 microns ⁽³⁾.

While HEPA filters cost more than basic screens, this air purifier build still costs far less than a commercial machine. It takes about five minutes to put together.

What You’ll Need

• Box fan (20-inch is standard).
• Four zip ties (or duct tape).
• 20×20 MERV 13 or HEPA filter.
• Screwdriver.

Step-By-Step

1. Prep the filter: Find the airflow arrow on the side of the filter frame. This arrow must point toward the fan.
2. Position the filter: Place the filter against the back of the fan (the intake side).
3. Secure it: Use zip ties through the fan’s grating or duct tape to seal the filter frame to the fan casing. Make sure there are no gaps for air to bypass the filter.

If the fan controls are on the back, set your speed before attaching the filter, or use a smart plug to turn it on and off.

Front vs. Back: Where Does the Filter Go?

You might see people taping filters to the front of the fan, but the back is the better spot.

When the filter sits on the back (the intake side), the fan pulls air through the screen. This traps dust before it hits the fan blades and keeps the motor cleaner. Mount it on the front and the blades cake with dust over time, which is a pain to clean. Only mount it on the front if your fan’s design makes rear-mounting impossible.

Are DIY Purifiers Efficient?

Yes, and the research backs it up. EPA testing found that the simplest build, a box fan with a taped-on MERV 13 furnace filter, reached a clean air delivery rate of about 111 cubic feet per minute, and that well-built DIY units can match commercial air cleaners at a fraction of the cost.

The design also scales. Building four MERV 13 filters into a cube around the fan, a setup known as a Corsi-Rosenthal box, raised the clean air delivery rate by roughly 260 percent in EPA testing. A thicker four-inch filter or a simple cardboard shroud on the back of the fan gives a smaller but real boost.

The trade-offs are noise and upkeep. Box fans move a lot of air but run loud, and a filter loaded with smoke and dust loses cleaning power quickly, so change it on a regular schedule during heavy smoke.

FAQs

Airing Out

Building your own air purifier is a satisfying project that saves money and helps your lungs. Whether you go with the bucket build, the furniture-style cabinet, or the simple box fan and filter, you are taking a real step toward cleaner indoor air.

The box fan and MERV 13 filter method is our top pick for speed and cleaning power. Just change the filter on a regular schedule, especially during smoke season, to keep the air moving freely.