Ask Kat: Will Purse Magnets Damage My Credit Cards?


this is a common concern for many of our customers. After all, there’s quite a bit of misinformation circulating about the circumstances under which magnets can scramble the magnetic strip on credit cards, but you know what? I’ve been using magnetic closures in bags for years now and never EVER had a problem with a demagnetized credit card or hotel key, I’ve always figured this to be a misunderstood risk, if not an exaggerated one.

But here’s the deal… since we’ll be calling for two such magnets in the flap closure for our new design, I thought it might be a good idea to be proactive this time and do a little research ahead of time, so I can offer a more scientific answer to the inevitable questions that will be coming…. and here’s a few things I found out!

1) Not all magnetic stripes are created equal. Did you know this? Because I sure didn’t! Evidently the magnetic stripe on the back of cards comes in two varieties.  Typical credit cards require a VERY  strong magnetic strength to demagnetize them, (typically ~4000 gauss), but because the magnetic stripe on hotel key cards and gift cards can be written over & over, it’s MUCH easier to de-magnetize them (by a magnetic field of 300 gauss or less).

2) It’s easy to tell if your card has a strong or a weak magnetic field. Hotel keys and other cards which can be re-written generally have stripes that are a light brown color, but the stripes on bank credit and ATM cards are very nearly black…In general, the darker the stripe, the stronger the magnetic stripe and the less susceptible it is to being scrambled by another magnetic field.

3) It isn’t the strength of the magnet that’s important, it’s the duration of exposure. Even the mightiest junkyard magnet won’t erase your card’s data if the exposure is brief, but that little refridgerator magnet that can barely hold up that cute little picture of your cat can — if the exposure is long enough. (don’t believe me? CLick HERE to watch a video created by CreditCards.Com)

4) The key to keeping your cards safe is to keep a bit of distance between the magnet and the magnetic strip on your card. In order for a magnet to scramble a magnetic strip, it’s pretty much going to have to come in direct contact with it. As a matter of fact, the magnetic field emitted by a cell phone can actually demagnetize a credit card if it’s allowed to be in direct contact with the magnetic strip for along enough period of time.

So…. what precautions can we take to keep our various cards safe?

First and foremost- Do not store your cards in such a way that the magnetic stripe is allowed to “get cozy” with another magnetic field. Here’s some practical, everyday ways you can keep all of your cards safe and operating correctly for years.

  1. Always store your cards in separate slots in your wallet or purse to prevent demagnetization or damage to the magnetic stripes. NEVER store your cards “stripe-to-stripe”, which can also cause de-magnetization! ( I never knew this!)
  2. If you don’t have credit card slots in your purse or wallet, look for individual plastic or paper credit card holders to protect each card.
  3. MRI machines are dangerous to credit cards. MRI stands for “magnetic resonance imaging,” and with good reason; these pieces of medical equipment use large magnets to create detailed images of things inside the body. The magnetic fields they create are so strong that you shouldn’t even bring your cards in the same room with one of these instruments.
  4. Be cautious around security tag deactivators. Some stores have small surfaces at checkout stands that a cashier can run a pricey item over to deactivate its security tag. Whether they will demagnetize your card however, is hit or miss. Some of these deactivators use radio waves to decommission the tag; they pose no threat to cards. Others use magnets, and those can cause damage. To be safe, always put your card back in your wallet promptly after paying.
  5. Our sew-in invisible magnets are actually LESS threatening to your cards than the old-style clamp-in magnets are. That’s because our disc magnets are encased within a plastic layer that’s roughly 1/32″ thick. That may not sound like much, but even that much distance can be enough to lower the magnetic field below the strength required to scramble a typical credit card, even if it’s placed in constant contact with the card. (Also, there’s usually going to be at least one other additional layer of fabric or foundation material between the magnet and the card, providing additional protection.)
  6. Never just drop your card into your handbag, allowing it to just tumble around loose. I know it’s tempting to do this when you’re in a hurry, especially with hotel key cards, but remember, it takes a far weaker magnetic field to deactivate your hotel key, so it’s actually MORE important to store them safely than your credit or ATM card.

And finally…

Despite claims of demagnetization, scratches and small bends are the #1 reason that cards have to be replaced. . Even the faintest scratches can do enough damage to make your card’s information unreadable. So, if your credit card malfunctions, look for scratches. Magnetic stripes can even be damaged by being stored in a HOT car.

Because anything that causes physical damage to that stripe has the propensity to keep it from being useful in an electronic transaction situation.

But, now it’s YOUR turn!

I really enjoyed researching this piece because I never realized how much I didn’t know about the magnetic stripes on the back of my cards! But how about you? Did you learn something new today? Does this post make you feel better about using magnetic snaps, or are there other questions you still might have?  

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  1. Linda Sanders on November 10, 2019 at 4:16 pm

    I found this article very interesting and will make some changes in my purse and wallet. Thank you for the information. I’ve just purchased your Flaptastic Bag at the Houston Quilt Show, can’t wait to get started. I have been making quilts to keep busy.

    Linda Sanders

    • Kat on November 11, 2019 at 9:25 am

      you are so welcomed and I hope you enjoy the process! 🙂

  2. Carla A Sabotta on April 15, 2021 at 7:17 pm

    Thank you very much for providing this information about purse magnets and credit cards. I recently made an in-the-hoop wallet that includes a magnetic snap closure, and didn’t want to avoid using it because of concern about credit cards.