Faraday bags tested: do they actually work?

A Faraday bag blocks all wireless signals: Wi-Fi, Bluetooth, mobile network, GPS and NFC. Or that is what most manufacturers claim. Here, those claims are tested.

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What is a Faraday bag?

A Faraday cage is a metallic enclosure that blocks electromagnetic signals. A Faraday bag is a portable version — a bag with a metallic lining that achieves the same effect.

Applications:

• Blocking a phone from location tracking
• Blocking car keys (preventing relay attacks)
• Transporting devices without them connecting to any networks

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How it is tested

Attenuation — the weakening of the signal — is measured in decibels (dB). An attenuation of 60 dB means the signal is one million times weaker. In practice: unreachable for normal receivers.

Test setup:

• Measure signal strength with device outside the bag (reference)
• Place device in the bag
• Measure signal strength again
• Difference = attenuation

Frequencies tested: 700 MHz (4G), 1800 MHz (4G/LTE), 2.4 GHz (Wi-Fi/Bluetooth), GPS L1 (1575 MHz).

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Test results

Mission Darkness MOLLE Pouch

Price: around €35

Frequency	Attenuation
700 MHz	78 dB
1800 MHz	82 dB
2.4 GHz	85 dB
GPS L1	74 dB

Excellent attenuation on all frequencies. The brand delivers what it promises. This is our recommendation for phone size.

Generic Faraday pouch (various sellers)

Price: around €10–15

Frequency	Attenuation
700 MHz	28 dB
1800 MHz	35 dB
2.4 GHz	42 dB
GPS L1	22 dB

Insufficient. An attenuation of 28 dB at 700 MHz means the signal can still penetrate with a sensitive receiver. Not suitable for serious use.

Conclusion on cheap alternatives: Most cheap Faraday bags on Amazon and similar platforms show no independent test results. Our measurements confirm that attenuation is insufficient for the intended protection purpose.

Mission Darkness Laptop bag

Price: around €95

Frequency	Attenuation
700 MHz	80 dB
1800 MHz	84 dB
2.4 GHz	88 dB
GPS L1	76 dB

Same quality as the smaller pouch, now for laptop size. Good for transporting laptops or tablets when you want to be certain they make no network connections.

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When do you need a Faraday bag?

For most people: probably never. A Faraday bag is a tool for specific situations:

• Protecting keyless entry car keys against relay attacks (thieves capture and copy the signal)
• Taking a phone to a location without tracking
• Isolating devices during forensic investigation or security testing

If you suspect your phone is compromised: airplane mode is the easier option for most situations. A Faraday bag adds value when you do not trust airplane mode.

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Which Faraday bag for which use case?

The attenuation figures above matter — but the required attenuation depends on what you are trying to do.

Stopping relay attacks on car keys: Relay attacks work by amplifying your key’s signal. Any meaningful attenuation — even 25 dB — makes this impossible: there is no signal left to amplify. A budget Faraday key pouch at €9 is more than sufficient for this purpose.

Keeping your phone offline for everyday use: If you want your phone genuinely offline during meetings, while travelling, or at home — not because you fear targeted surveillance, but as a habit — a budget Faraday phone pouch is a practical tool. 28–42 dB attenuation is not complete isolation, but it is enough to make your phone unreachable by ordinary receivers.

Serious counter-surveillance or forensic use: Here you need 70–80 dB. Only use Mission Darkness or similarly certified products. Budget products do not meet this requirement.

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Conclusion

The right choice depends on your use case. For relay attacks on car keys, a budget pouch works fine. For phone isolation as a habit, a budget pouch is usable. For serious counter-surveillance or forensic work: use Mission Darkness.

If you want a Faraday bag for complete isolation: Mission Darkness MOLLE Pouch for phone size, Mission Darkness laptop bag for larger devices.