Are Sewing Machine Bobbins All the Same? (for Beginners)

Bobbins are an intrinsic part of any sewing machine. If you’ve only started sewing you may only have a vague idea of what these little round mechanisms are and what they do. Most sewing machine bobbins look very similar too which may lead you to believe that they’re all identical, but is this true?

Though sewing machine bobbins have a superficially similar appearance, different brands of sewing machines tend to produce bobbins of varying shapes, diameters, heights, and depths to suit their specific sewing machine dimensions.

Using the wrong size and type of bobbin in your sewing machine can affect your stitch quality at best and may completely jam your machine and cause the thread to get tangled up at worst. It’s super important, therefore, that you always try to use the correct bobbin for your machine brand and type. Let’s find out more about sewing machine bobbins, their purpose, knowing which type to buy, and more.

What’s a Sewing Machine Bobbin?

A sewing machine bobbin is the small metal or plastic reel/spool that holds the lower thread in a sewing machine. These bobbins are situated at the bottom of the machine underneath the needle plate and thread is wound around the small cylinder in between each bobbin ‘wheel’.

The needle and thread at the top of the machine then pull on the thread from the bobbin to form the bottom seam, thus working together to complete a stitch.

Front Load Bobbin vs Top Load (Drop-in) Bobbin

You may have heard the terms ‘front load bobbin’ and ‘top load/drop-in bobbin’ – this simply refers to the two main types of bobbin loading systems in a sewing machine in which the bobbin is inserted into its bobbin case.

The older and slightly outdated front loading system requires the sewist to remove the accessory compartment on the machine using screwdrivers in order to change the bobbin, whilst a top loading or ‘drop-in’ bobbin system means that the bobbin can stay inside the machine for threading and only needs to be removed to be cleaned.

For beginner sewists, the pros Recommend using a sewing machine with a drop-in bobbin system as this is a much easier, fuss-free way of accessing and loading the bobbin. Most modern machines are made with drop-in bobbin loading systems and often come with a transparent compartment cover, allowing you to see how much thread is left on the bobbin as you work.

A big difference between the two systems is that the top loading drop-in systems tend to use plastic bobbins, whilst the older front loading systems provide you with the option to use metal bobbins. Why might some prefer metal bobbins? Well, metal bobbins tend to hold a lot more thread than plastic ones which is handy for big sewing projects since you won’t need to change the bobbin mid-way.

At the end of the day, you simply need to decide whether having more thread on the bobbin is a bigger plus than having a more convenient, easier way of loading the bobbin.

Do All Bobbins Fit All Sewing Machines?

No, bobbins are not universal to all sewing machines. Using a bobbin type that is too tall or too wide/small for your specific sewing machine will alter the stitch quality in your work and could very well damage the machine – think of it like diesel and gasoline fuel for your car (the car will run at its best on the fuel it was designed to take!).

Helen Harrison from the Crafty Sewing Sew blog explains that “if you use a long arm quilting machine, for example, a large bobbin size is ideal. But a small bobbin size would not deliver the quality of work you’re hoping for.”

What Are the Different Types of Bobbins?

Home sewing machine bobbins are most commonly made of metal, but the inexpensive and durable nature of plastic bobbins is making these an increasingly popular type. There are also aluminum bobbins available which are praised for their lightweight ‘quick wind’ quality due to a faster spin. Aluminum bobbins can get scratched easily though, so metal and plastic bobbins remain the popular types for now.

The most common bobbin types you’ll find in household sewing machines are:

A Style (Class 15): This type is available in plastic and metal and is roughly the size of a nickel (20.3 mm in diameter). It typically has a width of 11.7 mm and has a completely flat top and bottom with multiple holes on the wheel plates.

L Style: These are also the size of a nickel (20.3 mm diameter) but are slightly more narrow with a width of 8.9 mm. L Style bobbins have flat solid sides (no holes) and are available in plastic, metal, and aluminum.

M Style: This bobbin type is larger than the previous two, at about the size of a quarter (24.99 mm in diameter). M Style bobbins also feature multiple holes in the wheel plates and have a width of 10.7 mm. They’re also made in plastic, aluminum, and metal.

These are the most commonly used types of bobbins that can perform most sewing machine tasks. However there are over 60 types of bobbins in the sub-genre of A, L, and M styles in total as bobbins are made specific to each sewing machine type (i.e. long-arm, embroidery) and brand (Singer, Janome etc).

Why Do Sewing Machines Need Bobbins?

Sewing machines require bobbins to complete a stitch. Bobbins hold the thread and feed it through the machine which helps the upper thread make a stitch on the base of the fabric – so you simply can’t sew without a bobbin!

How Do I Know What Size Bobbin To Buy?

First off, check the manual that came with your sewing machine model. This will direct you first of all to whether a metal or plastic bobbin would suit it best. Next, look at the size of the bobbin case in your sewing machine – the dimensions of the bobbin case will help you determine which diameter bobbin will work best in your machine.

For further guidance, The Thread Exchange helpfully lists the compatible bobbin types for many well-known sewing machine brands here.

Are Bobbins Specific to Sewing Machines?

Yes, as above-mentioned bobbins cannot be used with just any sewing machine. Each sewing machine will require a specific type of bobbin in order to function correctly and produce quality work.

Always consult your brand manufacturer regarding the bobbin type to use and when in doubt, buy directly from the sewing machine’s brand website to ensure you get the appropriate bobbin style.

Why Do Bobbins Have Holes?

The majority of sewing machine bobbins have holes on the wheel plates. These are there for you to put your thread through (threading from the inside of the bobbin and out so the thread sticks out by a few inches). You then hold on to this end of the thread poking out while the thread is wound around the bobbin cylinder.

Of course, some bobbins don’t have holes which can make it tricky to wind if you’re unfamiliar with the process. Here’s a helpful video to winding bobbins without holes.