Over the years, you may have heard that you shouldn’t keep your smartphone and your hotel card in the same pocket, because the former could demagnetize the latter. And it would make sense with modern iPhones supporting MagSafe charging. The problem is that this advice is irrelevant in most cases, because the majority of hotel key cards you’ll come into contact with today use RFID technology – not magnetic strips – to store data. So while there are cases where a phone can affect a passcard, it’s pretty unlikely that this oft-discussed passcard rule will be added to the list of iPhone myths you should stop believing.
RFID cars — and similar NFC cards you can add to your digital wallet — store authentication data on a chip, not a strip. They communicate wirelessly with a door lock, when the customer places the card on a reader or holds the card near the reader. As these cards do not contain any magnetic components, they will not be affected by the magnetic fields of smartphones. Magnets may not affect your RFID key card, but foil certainly does.
How to tell the difference between RFID cards and magnetic cards
You can easily tell the difference between a magnetic card and an RFID card. A swipe card has a black or brown magnetic stripe on the back and you must slide it into a slot for the reader to receive the data encoded on it. RFID cards generally do not have a stripe on the back, or if they do, the stripe is not used for access. In terms of operation, you hold an RFID card against its reader, while magnetic cards are swiped or inserted into the door lock (as shown above).
A 2025 report from Print Plast says the failure rate for magnetic cards is 15 to 20 percent per guest stay, compared to less than 2 percent for RFID key cards, but it adds that RFID cards are “completely immune” to demagnetization. Although the risk of a smartphone impacting an access card is minimal, smartphone vendors can address degaussing risks. “Do not place credit cards, security badges, passports, or key fobs between your iPhone and the MagSafe charger, as doing so may damage the magnetic strips or RFID chips on these items,” Apple writes in a support document for iPhones that support MagSafe charging.
Best practices for hotel key cards
Print Plast said the main cause of hotel cards failing is an encoding error made at the front desk or time-based access rules that some hotels apply regardless of length of stay. For example, late check-outs may also render the card unusable after the normal check-out time. The same report also noted other issues that could affect key card operation, including physical damage, environmental reasons (water and temperature), and door lock mechanism malfunctions including low batteries.
Although it is prudent to keep your hotel key card next to a smartphone, you should determine the type of card before doing so. Many hotels have switched to RFID cards, and these will be safe from magnetic interference. For keycards confirmed to have a magnetic stripe, you should avoid placing the card next to MagSafe rings on iPhones that support it. It may be advisable to keep the card in another pocket or wallet. Another alternative is to request a mobile NFC key card (shown above), if available, which will be saved to your smart device, making unlocking the doors even more convenient.
