What Material Will Block GPS Signal

Ah, aluminum foil. You always knew there was some use for it. Now you know.

Aluminum foil is surprisingly effective at blocking GPS signals, thanks to a concept known as a Faraday cage. When you wrap a GPS tracker or similar device in aluminum foil, it blocks the radio signals the device relies on, making the tracker essentially useless.

The aluminum foil acts like a makeshift Faraday cage — a container made of conductive material, like metal, that blocks electromagnetic fields. When GPS signals hit the foil, they create currents in the material, which produce an opposing field that cancels out the GPS signal.

Here's how it breaks down:

• Aluminum foil as a shield: wrapping foil around a GPS device creates a barrier that blocks the radio signals.
• Faraday cage effect: this works just like a Faraday cage, where the conductive material cancels out signals trying to pass through.
• Impact on GPS tracking: the tracker loses its signal, disrupting its ability to function properly.

Understanding how something as simple as aluminum foil can interfere with GPS signals highlights the need to be mindful of how you handle and position GPS devices. Whether you're shipping something, using GPS for personal navigation, or tracking a vehicle, knowing this can help you avoid unintentional signal loss and keep your GPS working as intended.

Here's a quick step-by-step guide to wrapping a GPS device in aluminum foil to block its signal:

1. Gather materials: get a piece of aluminum foil large enough to fully cover the GPS device. You may need additional layers for better signal blocking.
2. Prepare the GPS device: turn the device off if possible, to ensure no data transmission occurs while wrapping.
3. Wrap the GPS device: place the device in the center of the foil and fold the edges over it, covering it completely. Smooth out any wrinkles so signals can't sneak through gaps.
4. Secure the wrapping: once the device is fully covered, add a second layer of foil for extra security, with no openings.
5. Test the signal block: check whether the signal is fully blocked by trying to locate the device with a tracking app. If it's not detectable, the foil is working.
6. Store or hide the wrapped device: place it somewhere secure where it won't accidentally get unwrapped.

Important note: if a GPS tracking device is there for a legitimate, legally authorized reason, you may be breaking the law by removing or disabling it. And if you believe a device was placed on you illegally, documenting it and contacting law enforcement before you remove or wrap it helps preserve it as evidence. See the legal section below.

Forests and mountains can be effective at blocking GPS signals, which is why a GPS tracker might struggle in these areas. Thick tree cover and the sheer size of mountains get in the way of the signal, making it hard for a device to connect with satellites.

If you're trying to block a GPS signal, sticking to areas with dense tree cover or rugged mountains is a good bet. Think about hikes deep in the woods or surrounded by mountains where your GPS or phone suddenly loses signal — that's exactly what happens when natural barriers get in the way.

But here's the thing: if you're heading into these areas, don't rely on your GPS alone. Carrying a backup map and compass is always smart, so you're prepared if the signal drops.

Metallic structures, like the ones found in cars, can block GPS signals.

That's one of the main reasons trackers malfunction from time to time — they can't connect to the network because the car's frame gets in the way.

The metal components of the car act as barriers, keeping the GPS antenna and receiver from communicating effectively with satellites. This is also why you shouldn't hide a GPS tracker in the trunk of a vehicle.

Tip: if you're renting a car, put the GPS device where it has a clear view of the sky, away from metal parts that could block the signal. We recommend the dashboard or underneath the car (GPS signals can reflect off the ground or other surfaces).

Tip: if you think someone might be tracking you without your consent, use a GPS detector to search different areas under your car, inside the dash, or inside the front end. Smart stalkers will know not to place a device inside the trunk — always think like the person you're trying to catch.

Concrete structures can completely block a GPS signal, especially in places like underground parking garages or buildings with thick concrete walls. You've probably noticed you never get a signal parking in one of these spots — now you know why.

If you're trying to stay off the grid, a concrete parking garage does the job. If it's underground, even better.

In an underground parking garage, the concrete walls, ceilings, and floors create a maze that GPS signals just can't get through.

Even above ground, concrete buildings can reflect GPS signals, making your location seem off or causing your GPS to give wrong directions.

So what can you do if concrete is messing with your GPS signal? If you're in an underground structure, the GPS will likely reconnect once you're back outside. For driving, consider a GPS device with preloaded maps that can guide you even when the signal drops, or keep a traditional map handy as a backup.

Related article: Can GPS Be Traced Back To Owner?

Large buildings like skyscrapers block GPS signals by obstructing the line of sight between the GPS device and the satellites. If you're trying to stop someone from tracking your location, a place with a lot of tall buildings can help.

The dense materials in these structures — concrete, steel, and glass — absorb and reflect GPS signals, making it hard for a device to connect. This interference creates "dead zones" where GPS tracking becomes unreliable or even impossible.

Pro tip: if you're trying to avoid GPS tracking, move through areas with tall buildings or stay close to structures made of dense materials like concrete or steel. The more these materials surround you, the more likely they are to disrupt the signal. Keep in mind this isn't foolproof, and combining it with other legal methods — like locating and disabling an unauthorized tracker — works better than relying on buildings alone.

GPS jammers are devices that disrupt GPS communication by scrambling the signal, making it impossible for a tracking system to determine location. Unlike the passive methods above, jammers are active transmitters — and as covered below, they're illegal to sell, buy, or operate in the U.S.