# Are sewing machine bobbins universal?

Source: https://stitchandhem.co.uk/blog/are-bobbins-universal
Published: 2026-10-12
Publisher: Stitch and Hem

**In short:** No. Bobbins look alike but come in several types, including class 15 (and the 15J variant), L style, class 66 and brand specific bobbins. They differ in height, diameter, side shape and material, and a bobbin that almost fits can cause tension trouble, birds' nests and skipped stitches. Always check your manual or the maker's part number before buying.

A tub of mixed bobbins is a common sight in sewing boxes, and many of them look identical. Yet a bobbin that is a fraction too tall, too narrow or the wrong shape can wobble in the case, unwind unevenly and throw the stitch tension out. Knowing the main bobbin classes helps you buy the right ones and explains why a perfectly threaded machine can suddenly start making loops underneath the fabric.

## Why bobbins are not interchangeable

The bobbin sits in a bobbin case or a drop-in holder under the needle plate, and the hook passes around it with every stitch. It has to spin freely and evenly, without rocking or rubbing. Small differences in height, diameter, the shape of the sides (flat or slightly domed), the centre hole and the material all change how it sits and how the thread feeds off.

When the bobbin is wrong, the bobbin thread tension changes, so the balance between upper and lower thread is lost. You may see loops on the underside, bobbin thread pulled to the top, or a tangle under the fabric. Plastic and metal bobbins also behave differently, so use the material your maker specifies; metal bobbins in a holder designed for plastic can affect sensors or tension on some machines.

## The main bobbin types

These are the bobbin classes you will see most often in shops and listings. The names are a useful starting point, but makers sometimes vary details within a class, which is why the part number matters.

| Type | Description | Commonly used in |
| --- | --- | --- |
| Class 15 | Flat sided, the most widespread domestic bobbin, in plastic or metal | Many domestic front loading and drop-in machines from various brands |
| Class 15J | A class 15 variant with slight differences, usually clear plastic | Some Janome and other domestic models; check your manual |
| L style | Shorter and flatter than class 15 | Some domestic, quilting and long arm machines and some embroidery models |
| Class 66 | Similar size to class 15 but with slightly domed sides | Many Singer drop-in machines |
| Brand specific | Bobbins made for one maker's machines, sometimes with colour marks or special shapes | Some Janome, Bernina and other models |

Common bobbin types

## Brand notes: Brother, Janome and Singer

Brother lists bobbins by part number for its domestic machines, and many of its models use a class 15 style bobbin; some use a different type, so match the part number in your manual. Janome uses class 15 or 15J style bobbins on many machines, but some models need Janome's own bobbins, which may carry coloured markings to identify them. Singer drop-in machines commonly use class 66 or class 15 bobbins depending on the model.

Because the same brand can use different bobbins across its range, the brand name alone is not enough. Check the manual, the maker's accessories page for your model number, or take an original bobbin with you to a sewing shop. Our [brother sewing machines compared](https://stitchandhem.co.uk/best/brother-sewing-machines-compared) and [janome sewing machines compared](https://stitchandhem.co.uk/best/janome-sewing-machines-compared) guides list the models covered.

[Compare Janome machines](https://stitchandhem.co.uk/best/janome-sewing-machines-compared)

## How to find the right bobbin for your machine

Wind bobbins evenly at a moderate speed so the thread lies in neat layers, and avoid overfilling them. A badly wound bobbin can cause the same symptoms as the wrong type. Our guide on [how to wind a bobbin](https://stitchandhem.co.uk/blog/how-to-wind-a-bobbin) covers the details.

1. Look in the manual, usually in the accessories or bobbin winding section, for the bobbin type and part number.
2. Search the maker's website for your exact model number and its accessory list.
3. Compare an original bobbin with any new ones side by side: height, side shape, centre hole and material should all match.
4. Buy bobbins listed by part number for your model, or a class clearly stated as compatible in the manual.
5. Remove any odd bobbins from your sewing box so they do not get mixed in again.

## Signs you are using the wrong bobbin

If the problems below started after you added new bobbins, try an original bobbin before adjusting tension. Fitting the correct bobbin often fixes the issue straight away. If it does not, rethread the upper thread with the presser foot raised and see [thread bunching under fabric](https://stitchandhem.co.uk/blog/thread-bunching-under-fabric) for more checks.

- Loops or a tangle of thread underneath the fabric.
- Bobbin thread showing on the top of the seam.
- A rattling or clicking sound from the bobbin area.
- The bobbin sitting proud of the holder or wobbling when you turn the handwheel.
- The bobbin thread breaking or jamming more than usual.

Note: Switch off and unplug the machine before removing the needle plate or cleaning the bobbin area. If the hook or timing seems damaged after a jam, stop using the machine and contact a qualified sewing machine engineer.

## Frequently asked questions

**Are class 15 bobbins universal?** They are the most common domestic type, but not universal. Many machines take class 15 bobbins, while others need 15J, L style, class 66 or brand specific bobbins. Check the manual or part number before buying.

**Can I use metal bobbins instead of plastic?** Only if the manual allows it. Some machines are designed for plastic bobbins, and metal ones can change tension or interfere with the bobbin holder. Use the material your maker specifies.

**Do Janome machines need special bobbins?** Many Janome machines use class 15 or 15J style bobbins, but some models need Janome's own bobbins. Look up the bobbin part number for your model before buying.

**Why does the wrong bobbin cause tension problems?** A bobbin that is slightly the wrong size or shape spins unevenly in the case, so the bobbin thread feeds off with varying resistance. That upsets the balance with the upper thread and causes loops or puckers. If you are buying a new machine, the [best sewing machines for beginners](https://stitchandhem.co.uk/best/best-sewing-machines-for-beginners) guide is a good place to start.

## Buying guides on this topic

- https://stitchandhem.co.uk/best/best-sewing-machines-for-beginners
- https://stitchandhem.co.uk/best/brother-sewing-machines-compared
- https://stitchandhem.co.uk/best/janome-sewing-machines-compared
- https://stitchandhem.co.uk/best/singer-sewing-machines-compared