How to test a Faraday bag

The honest home check

Put the powered-on phone fully inside. Close the bag the way the maker tells you to — full fold, full roll, full Velcro. Leave it long enough that a missed call or a failed Find My ping means something. Try a call from a second phone. Try Wi-Fi and Bluetooth pairing from outside.

If anything gets through, the bag failed that check. If nothing gets through, you still do not have a dB number. You have a pass on a noisy, uncontrolled test at one location.

What the home check misses

You do not control the tower, the phone’s bands, or the noise floor. A bag that blocks LTE in a basement can leak on a roof. GPS, NFC, and UWB are easy to skip if you only try a voice call.

You also do not test the bag after a hundred open-close cycles. Closures wear. Faraday Zone will re-test seals, not only new fabric.

What Faraday Zone will measure

Shielding effectiveness in dB on cellular, Wi-Fi, Bluetooth, GPS, and RFID/NFC, with the bag sealed as sold. We will say “untested here” until that exists for a SKU.

The first protocol is the Faraday Defense JACKET Pro phone bag. Equipment, bands, and pass/fail rules live on the lab page. We will not invent a curve to fill this article.

Standards you should ask brands for

IEEE 299 (or IEEE 299.1 for smaller enclosures) describes how to measure shielding of an enclosure. MIL-STD-188-125 is the EMP-oriented document many bag brands cite. A PDF with frequency, antenna, and date is evidence. The phrase “military grade” is not.