How to Soundproof Windows

Windows are often the main entry point for outside noise. Here's what actually works to reduce traffic, sirens, and street sounds.

If your apartment faces a busy street, you know the problem: traffic rumble, honking, sirens, late-night revelers, early-morning garbage trucks. Even on quieter streets, single-pane windows let in far more sound than you'd expect.

The fundamental challenge with windows is that glass transmits sound readily, and the seal between the window and frame degrades over time. Let's look at what you can realistically do about it.

Assess Your Windows First

Before spending money, identify what kind of windows you have and where noise is entering:

Check the Glass

Check the Seals

Run your hand around the window frame on a windy day. Feel any drafts? Those gaps let in sound too. Look for:

Solutions by Effectiveness (and Cost)

Level 1: Seal the Gaps

If there are air leaks around your windows, start here. This is cheap and often surprisingly effective.

Cost: Under $30 for most windows

Level 2: Heavy Curtains

Dense, floor-to-ceiling curtains help, though not as much as people hope. They work by:

Look for curtains marketed as "soundproof" or "acoustic," but be realistic—they'll take the edge off, not eliminate noise. Heavy blackout curtains provide similar benefits and help with light and temperature too.

Cost: $50-200 per window

Level 3: Cellular Shades

Honeycomb or cellular shades trap air in their pockets, providing some sound absorption. They're better than standard blinds but not as effective as heavy curtains for sound. Their main advantages are aesthetics and thermal insulation.

Cost: $50-150 per window

Level 4: Window Inserts

This is the most effective renter-friendly solution. Window inserts are secondary panels that fit inside your window frame, creating an air gap between the insert and your existing window. That air gap is what blocks sound.

How Window Inserts Work

The insert doesn't touch your original window. The space between them (ideally 2-4 inches) acts as a sound buffer. Better inserts use laminated glass or acrylic for additional sound blocking.

Noise reduction: 50-70% (higher frequencies)
Installation: Friction fit, no tools needed
Removable: Yes, completely

Window inserts are an investment, but for apartments with serious street noise, they're often the only solution that makes a meaningful difference.

Cost: $150-500+ per window depending on size and materials

Level 5: Window Replacement

Replacing windows with double or triple-pane soundproof windows is the most effective solution, but it's not realistic for most renters. If you own your place, it might be worth the investment for especially noisy areas.

The Bass Problem

Here's an important reality check: low-frequency sounds (bass, truck rumble, subway vibrations) are extremely difficult to block. They have long wavelengths that pass through most materials. Even expensive window inserts struggle with very low frequencies.

If your main noise issue is bass-heavy, manage expectations. You can reduce mid and high-frequency sounds (voices, horns, typical traffic) significantly, but you'll likely still hear and feel some low-frequency rumble.

DIY Window Plug

If you're on a tight budget and have a window you don't need to use, you can create a temporary window plug:

  1. Measure the window opening
  2. Cut rigid foam board (2" thick minimum) to fit snugly
  3. Cover with mass-loaded vinyl if you have it
  4. Wrap in fabric for appearance
  5. Press into the window opening

This blocks light entirely, so it's only suitable for windows you can live without. But for a spare room or bedroom where darkness is fine, it's remarkably effective for the cost.

Combining Approaches

The most effective approach usually combines multiple solutions:

  1. Seal all gaps and cracks
  2. Add window inserts (if budget allows)
  3. Install heavy curtains over the inserts
  4. Use white noise for remaining sounds

Each layer helps. You don't have to do everything at once—start with sealing gaps and see how much it helps before investing in more expensive solutions.