Promo magnets are mini billboards your customers see every day – but do they hold up to scrutiny?
Magnets are a great giveaway choice. They lie flat so all your info is easy to read, they’re seen every day, and they helpfully hold up pieces of paper.
It was this last aspect we set out to test. Our magnets are between 0.01” and 0.03” thick, which is not thick at all. We wanted to know if something that thin could actually hold up multiple sheets of paper, or if these magnets were going to end up being purely decorative mini posters. So we got stuck in.
How Magnets Work
Magnetism flows in a closed loop. Inside the magnet it travels from south to north, and then it leaves through the north pole and travels back around to the south. That north-to-south journey that takes place outside the magnet is what creates the magnetic field around the magnet.
Most magnets you use have a south pole on one end and a north pole on the other end. That means they’re magnetic on both ends. Their magnetic field looks like this:
Inside magnetic materials are very tiny magnets called magnetic domains. These also have a north and south pole. When all the magnetic domains inside the material face the same way, the material produces a magnetic field – in other words, it becomes magnetic.
In a magnet that’s magnetic on both sides, the magnetic domains all face south to north. In a magnet that’s only magnetic on one side, the magnetic domains are arranged in what’s called a Halbach array. The effect is a magnetic field that looks like a series of big arches on the strongly magnetized side, and tiny arches on the weak side. Here’s a diagram showing a cross-section of a Halbach array in a promo magnet:
Steel also contains magnetic domains, but they’re randomly aligned, so they’re not magnetic. When you put a magnet against them, the magnetic domains in the magnet pull the ones in the steel into alignment. This effectively extends the magnetic field from the magnet into the steel, and that’s why they stick together. In a Halbach array, the weakly magnetized side is not strong enough to pull those magnetic domains in the steel into line, but the strongly magnetized side is – so only that side sticks.
The reason putting paper under your magnet causes it to fall off is because you’re creating distance between the magnetic domains in the magnet and the ones in the steel, until at some point, the magnetism can’t flow between them and the magnet field is broken. The question is, how much distance – measured in pages of paper – can each magnet get through?
Method
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We placed a piece of standard 20lb printer paper between the magnet and the steel.
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We waited a few seconds, and if the magnet and paper stayed stuck to the steel, we added another piece of paper.
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We repeated step 2 until the magnet fell off the steel, then counted how many pages the magnet had managed to hold.
Video
Key Takeaways
Look at the Magnet’s Volume
Initially, we thought maybe a magnet’s area or its thickness could determine magnet strength. The logic was that more magnet (either because the magnet is larger or thicker) would mean more magnetic domains to bond with the steel, and therefore a stronger connection, and therefore more pages.
However, neither of these factors on their own correlated closely consistently with a magnet being able to hold more pages. We had to take both thickness and area into account, so we looked at volume – area multiplied by thickness. The correlation between a higher volume and more pages was stronger than with area and thickness individually.
The median number of pages our magnets held was 4. Six magnets in our test held at least 6 pages, and all of those six magnets had volumes of at least 0.32 inches cubed (in³). For reference, the median volume was 0.18in³, so these six definitely have high volumes. On the flip side, eight of our magnets held 3 or fewer pages. Seven of those eight magnets had a volume equal to or less than 0.14in³ – below the median volume.
From these results, we can say that magnets that can hold a higher-than-average number of pages also tend to have higher volumes. And magnets that can hold a lower-than-average number of pages tend to have lower volumes.
Volume wasn’t a perfect determiner of magnet strength. The magnet with the largest volume (0.72in³) came out joint top, holding 8 pages – but the magnet with the second-largest volume (0.7in³) held half that many pages. However, overall, if there’s one indicator you can use to judge a magnet’s strength when you’re shopping, I’d say it’s the volume.
Two Magnets Were Able to Hold 8 Pages
That’s a lot! As you’ll remember from 20 seconds ago, one of these was the magnet that had the highest volume in the test. It’s a 4”x6” rectangle that’s 0.03” thick, giving it a volume of 0.72in³. So that fits in with our thesis that in general, the higher the volume of the magnet, the more pages it will hold.
Irritatingly, the other magnet that held 8 pages does not fit that theory. It’s also a rectangle, and also 0.03” thick, but its dimensions are 5”x3”, giving it a volume of 0.45in³. That’s above the 0.18in³ median volume, but only the sixth largest volume in the test.
One thing that sets this magnet apart is the proportions between the lengths of its sides. The ratio of its sides (5:3) is the second-largest in the test, i.e it’s a longer and thinner rectangle than all but two of the other magnets. Those other two magnets are both 3.5”x2” and only 0.01” and 0.02” thick respectively.
If we think about how one-sided magnets work, it could be that the narrower shape requires the magnetic domains to be set up in a different way that makes them more effective – as long as the volume is still high. That would explain why the large and long rectangle was stronger than the other rectangles, but the small and long rectangles were not stronger.
Promo Magnet Buying Guide
Here’s the lowdown on which magnet you should actually buy, based on size and shape.
Best Big Magnet
At 4”x6” and a thickness of 0.03”, this magnet has the largest volume in the test and the joint-third-largest area. (It’s big, is what I’m saying.) It was also one of only two magnets that held 8 pages.
Best Small Magnet
This magnet is only 2”x3” and 0.02” thick, but it held four pages, the same as the largest magnet in the test.
Best Circle Magnet
With a 4” diameter, this circular magnet beat not only all the other circles, it came joint second in the whole test, holding 7 sheets of paper without falling.
Best Square Magnet
This 4”x4” square magnet is the other magnet that came in second, holding 7 pages.
Best Rectangle Magnet
XL Rectangle Magnet (Q41684) 4”x6”
Large Rectangle Magnet (Q24436) 5”x3”
Both of these rectangular magnets held 8 pages without falling – the best in our test. If you like rectangles that are long and thin, rather than more square, go with the 5”x3” option.
The Bottom Line
Our promo magnets are stronger than they look. Four of them held at least 7 pages, and even our worst-performing magnet held two pages without falling – that’s impressive, considering how thin they are.
While there wasn’t one single factor that determined which magnets would hold the most pages with 100% accuracy, the volume (area multiplied by thickness) was a fairly reliable indicator. Magnets with higher volumes tended to hold more pages, so stick with those next time you’re shopping for promo magnets.
| Q# | Name | Image + Clip | Dimensions + Volume | Number of Pages It Successfully Held | View Product |
|---|---|---|---|---|---|
| Q994 | Circle Magnet |
|
1.5″ Diameter x 0.02″ Thick 2in² Area 0.04in³ Volume |
3 | View Product |
| Q1656 | Creative Business Card Magnet |
|
3.5″W x 2″H x 0.02″ Thick 7in² Area 0.14in³ Volume |
2 | View Product |
| Q1677 | Rectangle Magnet |
|
2″W x 3″H x 0.03″ Thick 6in² Area 0.18in³ Volume |
4 | View Product |
| Q12343 | Circle Magnet |
|
1.5″ Diameter x 0.03″ Thick 2in² Area 0.06in³ Volume |
3 | View Product |
| Q12344 | Circle Magnet |
|
2″ Diameter x 0.03″ Thick 3in² Area 0.09in³ Volume |
3 | View Product |
| Q12346 | Circle Magnet |
|
3″ Diameter X 0.03″ Thick 7in² Area 0.21in³ Volume |
4 | View Product |
| Q12525 | Circle Magnet |
|
3″ Diameter X 0.02″ Thick 7in² Area 0.14in³ Volume |
3 | View Product |
| Q19231 | Large Circle Magnet |
|
4″ Diameter x 0.02″ Thick 13in² Area 0.26in³ Volume |
5 | View Product |
| Q24433 | Large Circle Magnet |
|
4″ Diameter x 0.03″ Thick 13in² Area 0.39in³ Volume |
7 | View Product |
| Q24436 | Large Rectangle Magnet |
|
5″W x 3″ H x 0.03″ Thick 15in² Area 0.45in³ Volume |
8 | View Product |
| Q41629 | Large Square Magnet |
|
4″W x 4″ H x 0.02″ Thick 16in² Area 0.32in³ Volume |
7 | View Product |
| Q41684 | XL Rectangle Magnet |
|
4″W x 6″H x 0.03″ Thick 24in² Area 0.72in³ Volume |
8 | View Product |
| Q41685 | XL Circle Magnet |
|
5″ Diameter x 0.03″ Thick 20in² Area 0.6in³ Volume |
6 | View Product |
| Q54248 | Square Magnet |
|
4″W x 4″ H x 0.01″ Thick 16in² Area 0.16in³ Volume |
4 | View Product |
| Q54249 | Square Shaped Magnet |
|
3″W x 3″H x 0.02″ Thick 9in² Area 0.18in³ Volume |
4 | View Product |
| Q54250 | Circle Magnet |
|
4″ Diameter x 0.01″ Thick 13in² Area 0.13in³ Volume |
3 | View Product |
| Q54251 | Circle Magnet |
|
3″ Diameter x 0.01″ Thick 7in² Area 0.07in³ Volume |
3 | View Product |
| Q54253 | Rectangular Business Card Magnet |
|
3.5″W x 2″ H x 0.01″ Thick 7in² Area 0.07in³ Volume |
4 | View Product |
| Q63666 | Rectangle Magnet |
|
4″W x 6″H x 0.02″ Thick 24in² Area 0.48in³ Volume |
4 | View Product |
| Q63677 | Rectangle Magnet |
|
5″W x 7″H x 0.02″ Thick 35in² Area 0.7in³ Volume |
4 | View Product |
| Q63679 | Rectangle Magnet |
|
3″W x 4″H x 0.02″ Thick 12in² Area 0.24in³ Volume |
3 | View Product |
| Q63993 | Rectangle Magnet |
|
2″W x 3″H x 0.02″ Thick 6in² Area 0.12in³ Volume |
4 | View Product |
| Q63994 | Square Magnet |
|
5″W x 5″H x 0.02″ Thick 25in² Area 0.5in³ Volume |
6 | View Product |
Natasha Lavender
Natasha is an experienced writer and editor who has covered topics including technology, health and safety, business, and pop culture. Her work has been published by Good Housekeeping magazine, Forbes, Success, and more.
