What Do Faraday Bags Block (and What Don't They)?

Signals a well-built Faraday bag typically attenuates

An intact, well-constructed Faraday bag can meaningfully reduce these common consumer signal types:

• Cellular (2G through 5G sub-6 GHz bands)
• Wi-Fi (2.4 GHz and 5 GHz)
• Bluetooth (2.4 GHz ISM band)
• GPS/GNSS reception (around 1.575 GHz for GPS L1)
• RFID and NFC (125 kHz and 13.56 MHz)
• Keyless entry / key fob signals (typically 315 MHz or 433 MHz depending on region and vehicle)

“Typically” is doing real work in that sentence. Whether a specific bag actually attenuates all of these depends on its shielding material, construction, and closure — covered in more depth in Do Faraday bags actually work?

Where the real limits are

Very high frequencies (mmWave 5G). 5G networks use two very different frequency ranges: “sub-6 GHz,” which behaves like most other cellular signals and is well within what standard Faraday shielding handles, and “mmWave” — above 24 GHz, used for very high-speed, short-range 5G connections. mmWave is a meaningfully different engineering problem: it needs denser weaves or additional shielding layers to attenuate effectively, and general-purpose consumer Faraday bags aren’t automatically built or tested for it. If mmWave-specific blocking actually matters for your situation, that’s worth confirming directly with the manufacturer rather than assuming a bag handles it just because it handles everything else.

Devices with multiple radios. A modern phone doesn’t use one signal — it can be running cellular, Wi-Fi, Bluetooth, and GPS at once, each at a different frequency. A bag that’s genuinely effective at blocking one of these isn’t automatically as effective at all of them; testing (where it exists) needs to cover the actual bands the device uses, not just one representative frequency.

Anything not related to radio signals at all. This is worth stating plainly because it’s an easy assumption to make incorrectly: a Faraday bag blocks or reduces radio communication. It does nothing about malware already on a device, data already stored on it, account security, or encryption. Signal isolation and device security are different problems — see What a Faraday bag can’t do for more on this distinction.

The honest way to think about coverage

The useful question isn’t “does this Faraday bag block everything” — it’s “does this bag attenuate the specific signals I actually care about, and is there any real evidence for that beyond the listing’s own wording.” A bag can be excellent for phone and key-fob frequencies and simply untested for mmWave 5G, and that’s a completely reasonable, honest limitation rather than a flaw — as long as it’s disclosed rather than papered over with “blocks everything” language.

Frequently asked questions

Do Faraday bags block 5G?

Sub-6 GHz 5G, generally yes, the same way they handle other cellular bands. mmWave 5G (above 24 GHz) is a separate, harder engineering problem that standard consumer bags aren’t automatically built or tested for.

Do Faraday bags block satellite trackers (e.g., AirTags)?

Trackers that rely on Bluetooth and crowd-sourced network signals to report location are generally within the frequency range Faraday bags attenuate, the same way phone Bluetooth is. As with everything else here, actual performance depends on the specific bag.

Can a Faraday bag block a signal it wasn't designed for?

Not reliably. A bag built and sealed for phone-range frequencies isn’t guaranteed to perform the same way at a very different frequency, like mmWave 5G or certain industrial RFID bands. Coverage is specific, not universal.

Is there a bag that blocks literally everything?

No consumer product is verified against every frequency in use today — see the Claim Check above. Treat any listing claiming total coverage with skepticism, and look for a stated frequency range instead.