The Complete Guide to Faraday Bags
A Faraday bag blocks electromagnetic signals from reaching your devices. Named after scientist Michael Faraday, these pouches create a “cage” that prevents cell signals, WiFi, Bluetooth, and GPS from passing through. This guide covers everything you need to know about choosing and using Faraday bags.
What is a Faraday Bag?
A Faraday bag is a portable enclosure made with conductive materials (usually metalized fabric or copper mesh) that blocks RF signals. When you place a phone, key fob, or laptop inside and seal it properly, the device becomes electronically invisible.
Common uses:
- Privacy protection from location tracking
- Key fob signal blocking for car theft prevention
- Device security during travel
- Forensic evidence preservation
- RFID/NFC blocking for cards and passports
Choosing the Right Faraday Bag
The best Faraday bag depends on what you need to protect:
Phone Faraday Bags
Compact pouches designed for smartphones. Look for dual-layer shielding and reliable closures.
Read our complete guide to Faraday bags for phones
Laptop Faraday Bags
Larger sleeves and bags for notebooks. Size matters here, so check dimensions carefully.
Read our complete guide to Faraday bags for laptops
Key Fob Pouches
Small signal-blocking pouches for car keys. Essential if your car uses keyless entry.
Our Top Recommendations
We tested multiple Faraday bags with RF meters. See which ones actually deliver on their claims.
Read the Ultimate Faraday Bag Buying Guide (2026 Edition)
How Faraday Bags Work
Faraday bags work through electromagnetic shielding. The conductive layer reflects and absorbs incoming radio waves before they reach your device. The effectiveness depends on:
- Material conductivity
- Seal quality (gaps let signals through)
- Frequency range covered
Common Problems
Why Do Faraday Bags Stop Working?
Faraday bags can degrade over time. Worn spots, damaged closures, and material fatigue all reduce effectiveness.
Learn why Faraday bags stop working and how to fix them
Testing Your Faraday Bag
The simplest test: put your phone inside, seal it completely, then call it from another phone. If it rings, the bag is not working. For more precise measurements, use an RF meter.
Learn about Tri-Field EMF Meters for testing
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Last updated: January 2026