Are Sewing Machine Bobbins Universal? (Spoiler: They're Not)

Sewing machines only come with a few bobbins, so at some point you're going to want to buy more. But here's something every sewist needs to know before they head to the craft store: bobbins are NOT universal. You can't just grab the first pack you see off the shelf.

A friend called me a few weeks ago because her thread kept tangling underneath her machine and she couldn't figure out why. When I took a look, I immediately spotted the problem — she was using the wrong type of bobbin. You could literally hear it bouncing around in the bobbin case. Her machine would only form a few stitches before birdnesting. I swapped in the correct bobbin and the problem was instantly fixed.

It's such a simple thing, but it makes all the difference.

Types of Bobbins

There are over 60 different types of bobbins. Using the wrong one can cause your machine to skip stitches, tangle thread, or not work at all. And in some cases, it can even damage your machine. The only way to know for sure which bobbin your machine uses is to check your manual. That said, most home sewing machines use one of these three common types:

Class 15 (A Style) — The most common bobbin type for home sewing machines. Class 15 bobbins have flat sides, a diameter of 20.3mm (about the size of a nickel), and a width of 11.7mm. Both my Brother CS7000x and Bernette b79 use this size. If your machine takes Class 15 bobbins, you're in luck — they're easy to find just about anywhere.

L Style — Another common type used in domestic sewing machines. L Style bobbins have the same diameter as Class 15 bobbins and also have flat sides, but they're narrower at approximately 8.9mm wide. They look nearly identical to Class 15 bobbins at first glance, so it's worth double-checking which one your machine requires. They are not interchangeable.

M Style — Less common but still widely used, particularly in longarm quilting machines and industrial sewing machines. M Style bobbins are larger, about the size of a quarter, with a diameter of around 24.9mm and a width of 10.7mm.

How to Find the Right Bobbins for Your Machine

The safest place to buy bobbins is directly from your machine's manufacturer. That's the only way to guarantee the right fit and quality. If you want to save money, generic bobbins can work, but buy carefully. I've purchased generic Class 15 bobbins in bulk that worked perfectly fine, but I've also had to throw some away because they were visibly warped right out of the package. Stick to reputable sellers and read the reviews before buying.

One more thing worth knowing: some bobbin types come in both metal and plastic versions. Even if the size is the same, you generally shouldn't switch between metal and plastic without checking your manual first. Using the wrong material can throw off your lower thread tension, cause premature wear, or prevent your machine's thread-low sensor from working correctly, if your machine has one.

The good news is that neither material is superior. Both metal and plastic bobbins work well and are surprisingly durable. Just use whichever type your machine recommends.

How Many Bobbins Do I Need?

Honestly? You can never have too many. I have many extra bobbins on hand so that I don’t have to unwind them to thread a new color.

I suggest that you get a set of bobbin clamps or a bobbin holder to keep your bobbins and matching thread spools organized together.

Your machine probably came with 3–5 bobbins. I'd recommend picking up at least a pack or two more. It's a small investment that makes your sewing life a lot easier.