In short, no. The magnetic strip on a hotel keycard (or on a credit card, for that matter) requires a considerably more intense magnetic field to erase or damage it than will ever be generated by an ordinary smartphone. They deactivate the magnetic strip key cards yes but not the new RFID key cards.

While it is a common travel myth that a smartphone will "wipe" or deprogram a hotel key card just by touching it, the reality is that it is highly unlikely for a modern phone to erase a card's data. Most hotel key cards use Magnetic Stripe (Magstripe) technology or Radio Frequency Identification (RFID). Magstripe cards can be erased by very strong magnets, but the magnets inside a smartphone's speakers or MagSafe connectors are generally too weak to flip the magnetic particles on a standard card stripe unless held together for an extended period. Most modern hotel keys in 2026 use RFID or "NFC" (Near Field Communication) chips, which are entirely unaffected by magnetic fields. The reason your key card often stops working is usually due to physical wear and tear, scratches on the stripe, or the front desk simply encoding the card with an incorrect checkout date. If your card fails, it is almost always an encoding error or physical damage rather than "interference" from your phone. However, keeping the card in a separate pocket remains a good habit simply to prevent the phone's screen from being scratched by the card's plastic edges.