{"id":3549,"date":"2026-10-21T18:44:04","date_gmt":"2026-10-21T10:44:04","guid":{"rendered":"http:\/\/www.dibenzoylmethane.com\/blog\/?p=3549"},"modified":"2026-10-21T18:44:04","modified_gmt":"2026-10-21T10:44:04","slug":"what-is-the-magnetic-hysteresis-of-a-bar-magnet-4063-45ae42","status":"publish","type":"post","link":"http:\/\/www.dibenzoylmethane.com\/blog\/2026\/10\/21\/what-is-the-magnetic-hysteresis-of-a-bar-magnet-4063-45ae42\/","title":{"rendered":"What is the magnetic hysteresis of a bar magnet?"},"content":{"rendered":"

Hey everyone, it\u2019s Jake here\u2014head of product over at Bar Magnets Co. I\u2019ve been geeking out with magnets for over a decade, and the question I get most from customers, especially when they\u2019re buying bulk bar magnets for projects, is: \u201cWhat\u2019s this magnetic hysteresis thing I keep seeing in specs?\u201d It\u2019s not just some jargon we throw around to sound smart\u2014understanding it can save you money, help you pick the right magnet for your job, and even make your projects work way better. Let\u2019s break this down like we\u2019re grabbing a coffee and troubleshooting a project, no stuffy textbook jargon. Bar Magnets<\/a><\/p>\n

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First, let\u2019s start with the basics everyone knows: a bar magnet has two poles, right? North and South, and that\u2019s why it sticks to fridges, pulls on other magnets, and works in everything from motors to sensors. But here\u2019s the thing\u2014when you start talking about magnets as materials, not just the bar magnets you buy at a hobby shop, they don\u2019t just snap into their magnetic state. That\u2019s where hysteresis comes in. The fancy definition is something like \u201cthe lag between an applied magnetic field and the material\u2019s resulting magnetization,\u201d but let\u2019s make it real.<\/p>\n

Imagine you\u2019ve got a blank, non-magnetic iron bar. You wrap a coil of wire around it, hook it up to a power supply, and turn on the electricity. That makes an external magnetic field around the iron\u2014let\u2019s call that the \u201capplied field.\u201d As you turn up the power (crank the field higher), the iron atoms\u2019 tiny magnetic domains (think of them like tiny, little bar magnets inside the metal) start lining up. At first, they flip pretty easily, so the magnetization of the iron bar jumps up fast. But once most domains are lined up, cranking the power more barely changes how magnetized the bar gets\u2014we hit what\u2019s called saturation. That\u2019s the max magnetization that iron can hold, no matter how much external field we throw at it.<\/p>\n

Now, here\u2019s the lag part. If you turn the power down, the domains don\u2019t just flip back to zero right away. Some of them get stuck lined up, like how a couch cushion stays bent a little when you lean on it. So when the applied field goes back to zero, the iron bar is still magnetized\u2014that\u2019s why a plain iron bar can turn into a permanent bar magnet if you leave it in a strong field. That leftover magnetization is called remanence (or retentivity, if you wanna get technical). But if you want to demagnetize it, you don\u2019t just turn the power off. You have to flip the direction of the external field (reverse the current in the coil) and slowly crank it up until the bar stops being magnetized. The amount of reverse field you need to wipe out all the magnetization is called coercivity.<\/p>\n

All this back-and-forth\u2014applied field going from positive to negative to positive, magnetization following behind, not matching exactly\u2014makes a loop. We call this the hysteresis loop, and every magnetic material has its own unique shape for it. For bar magnets, that loop is super important because it\u2019s what makes them permanent. Let\u2019s cut to why this matters for you, especially if you\u2019re buying bar magnets for industrial, commercial, or even big hobby projects.<\/p>\n

Think of two common types of magnets we sell at Bar Magnets Co.: neodymium bar magnets and alnico bar magnets. Neodymium is that super strong rare-earth magnet you know that can lift 10x its weight. Its hysteresis loop is super wide\u2014meaning it has super high coercivity. That means it takes a lot of reverse field to demagnetize it, so once it\u2019s magnetized, it stays that way, even if you drop it (carefully) or expose it to weak external fields. Alnico bar magnets, on the other hand, have a narrower loop. They\u2019re still strong, but they\u2019re way more prone to losing their magnetism if they get hit with a reverse field or get too hot. That\u2019s why you\u2019d never use an alnico bar magnet in a high-torque motor, but they work great for things like guitar pickups where you want a more stable, consistent field over time.<\/p>\n

Wait, let\u2019s talk about a common mistake we see customers make all the time. Some folks think all bar magnets are the same, but their hysteresis curve is what separates the ones that\u2019ll last 10 years vs. the ones that\u2019ll fizzle out in a year. For example, if you\u2019re making a custom sensor that needs a super consistent magnetic field\u2014no fluctuations\u2014you need a magnet with a straight, narrow hysteresis loop. That way, its magnetization won\u2019t change even if it\u2019s near other magnets or gets small temperature swings. If you grab a neodymium bar magnet, that\u2019s exactly what you get. But if you use a cheaper ceramic bar magnet (another type we sell, by the way) for that job, its coercivity is lower, so over time, small external fields will nudge its domains around, and the field strength will drop.<\/p>\n

Another real-world example: we had a customer last year who was making custom door latches for commercial fridges. They initially bought ceramic bar magnets because they were cheaper, but within 6 months, half the latches weren\u2019t sticking. Turns out, the fridges had compressors with strong magnetic fields nearby that were slowly demagnetizing the ceramic magnets\u2014their narrow hysteresis loop couldn\u2019t hold up to that. They switched to our neodymium bar magnets, which have way higher coercivity, and they haven\u2019t had a single issue since. That\u2019s the kind of problem hysteresis is directly responsible for, and it\u2019s why paying attention to it (instead of just going for the lowest price) saves you a ton of headaches and rework.<\/p>\n

Now, let\u2019s get back to that hysteresis loop for a sec, because it\u2019s not just about materials. The energy lost when you cycle the magnetic field back and forth is called hysteresis loss. That\u2019s a big deal for motors and generators, right? Every time a magnetic material flips its domains, it uses a tiny bit of energy, which turns into heat. For bar magnets that are in static use\u2014like fridge magnets or shelf displays\u2014this loss is basically zero, so you don\u2019t have to worry about it. But if you\u2019re using bar magnets in a rotating motor, that loss adds up over time. That\u2019s why motor designers pick specific magnet materials with lower hysteresis loss to make their motors more efficient. At Bar Magnets Co., we work with a ton of motor engineers to pick the exact bar magnet material that balances strength, coercivity, and energy loss for their build.<\/p>\n

Wait, let\u2019s clear up a myth real quick. Some people think that hysteresis is a bad thing, but it\u2019s all about context. For permanent bar magnets, we actually want high hysteresis\u2014meaning they retain their magnetization, don\u2019t demagnetize easily, and have a stable field. That\u2019s a good thing. For electromagnets or transformers, we want low hysteresis so we don\u2019t waste energy on heat. So it\u2019s not a flaw in the material\u2014it\u2019s just a property that we design around for specific uses. That\u2019s one of the coolest parts of working with magnets: the same property that makes bar magnets stick to your fridge is what makes motors run efficiently, depending on how you use it.<\/p>\n

Let\u2019s tie this back to our customers, because that\u2019s who this is for. Whether you\u2019re a small business owner making custom products, an engineer designing industrial equipment, a hobbyist building a robot, or someone just replacing a broken fridge magnet, understanding a bar magnet\u2019s magnetic hysteresis will help you pick the right magnet for the job. If you need a magnet that\u2019s tough, won\u2019t lose strength, and works in tough conditions (high temps, near other magnets, heavy use), go for a rare-earth or alnico bar magnet\u2014their wide hysteresis loops are built for that. If you need something cheap for a temporary project, a ceramic bar magnet might work, just know it\u2019ll demagnetize over time in certain environments.<\/p>\n

At Bar Magnets Co., we don\u2019t just sell magnets\u2014we help you pick the right ones. We\u2019ve spent years testing different materials, tracking how their hysteresis curves perform in real-world use, and building relationships with customers who need specific magnet specs. A lot of suppliers will just sell you the cheapest bar magnet, but we\u2019ll ask you questions like: Where will this magnet be used? What temperature will it be exposed to? How strong does the field need to stay? Those questions help us point you to the magnet with the perfect hysteresis properties for your project, so you don\u2019t waste money on something too strong or end up with something that breaks after a few months.<\/p>\n

Let\u2019s do a quick recap to make sure we didn\u2019t skip anything: Magnetic hysteresis is the lag between an applied magnetic field and a bar magnet\u2019s resulting magnetization. It comes from the tiny atomic domains inside the metal that don\u2019t line up perfectly when the field changes, and don\u2019t flip back when the field is removed. This creates a hysteresis loop that\u2019s unique to each magnet material, which tells you how well the magnet holds its strength (coercivity and remanence). For permanent bar magnets, high coercivity from a wide loop is a good thing\u2014it means a long-lasting, stable magnet. For rotating equipment like motors, hysteresis loss is something to keep in mind to keep energy efficiency up.<\/p>\n

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If you\u2019re in the market for bar magnets for any project\u2014big or small\u2014and you\u2019re not sure which type is right for you, don\u2019t second-guess it. Hysteresis is a super important property, but you don\u2019t have to be a magnetic physicist to figure it out. Just reach out to our team here at Bar Magnets Co., tell us what you\u2019re building, and we\u2019ll hook you up with exactly the magnets you need. We\u2019ve got bar magnets in all sizes, materials, and strengths, and we\u2019re happy to walk you through all the specs, including their hysteresis characteristics, so you can make a confident purchase without the confusion. Stop guessing and start getting the right magnets for your project\u2014we\u2019re here to help.<\/p>\n

Disc Magnets<\/a> References<\/p>\n

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  1. Cullity, B. D., & Graham, C. D. (2009). Introduction to Magnetic Materials. Wiley.<\/li>\n
  2. O\u2019Handley, R. C. (2000). Modern Magnetic Materials: Principles and Applications. Wiley.<\/li>\n
  3. Zurek, S., et al. (2018). Magnetic Hysteresis: From Fundamentals to Applications. IOP Publishing.<\/li>\n<\/ol>\n
    \n

    Dongguan Jinconn New Material Holdings Co., Ltd.<\/a>
    We’re well-known as one of the leading bar magnets manufacturers in China, featured by quality products and low price. Please rest assured to buy bulk advanced bar magnets in stock here from our factory. We also accept customized orders.
    Address: Xiaohe Industry Zone, Daojiao Town, Dongguan City,Guangdong Province,China
    E-mail: lena@jinconn.com
    WebSite:     https:\/\/www.jinconnmagnet.com\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

    Hey everyone, it\u2019s Jake here\u2014head of product over at Bar Magnets Co. I\u2019ve been geeking out … What is the magnetic hysteresis of a bar magnet?<\/span>Read more<\/a><\/p>\n","protected":false},"author":281,"featured_media":3549,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[3512],"class_list":["post-3549","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry","tag-bar-magnets-4a22-45e50b"],"_links":{"self":[{"href":"http:\/\/www.dibenzoylmethane.com\/blog\/wp-json\/wp\/v2\/posts\/3549","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.dibenzoylmethane.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.dibenzoylmethane.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.dibenzoylmethane.com\/blog\/wp-json\/wp\/v2\/users\/281"}],"replies":[{"embeddable":true,"href":"http:\/\/www.dibenzoylmethane.com\/blog\/wp-json\/wp\/v2\/comments?post=3549"}],"version-history":[{"count":0,"href":"http:\/\/www.dibenzoylmethane.com\/blog\/wp-json\/wp\/v2\/posts\/3549\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.dibenzoylmethane.com\/blog\/wp-json\/wp\/v2\/posts\/3549"}],"wp:attachment":[{"href":"http:\/\/www.dibenzoylmethane.com\/blog\/wp-json\/wp\/v2\/media?parent=3549"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.dibenzoylmethane.com\/blog\/wp-json\/wp\/v2\/categories?post=3549"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.dibenzoylmethane.com\/blog\/wp-json\/wp\/v2\/tags?post=3549"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}