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Should I use one size smaller for my bobbin thread?

When it comes to sewing, the quality of the bobbin sewing thread is just as important as the top thread. The bobbin thread is the one that goes through the bottom of the fabric, and it is crucial to make sure it is the correct type of thread and size.

Top three common question

  • One common question that arises for many sewers is if they should use a smaller size thread for the bobbin. If your goal is to achieve a perfect stitch, then the answer is yes. Using a smaller thread for the bobbin can help improve your stitching quality, as it reduces the thickness of the thread beneath your fabric. This creates less bulk, which in turn makes the stitches flatter and smoother.
  • When the bobbin thread is smaller than the top thread, it allows the stitches to form more evenly. This is because the top thread is heavier, and the smaller bobbin thread allows it to knit, forming a flatter stitch. On the other hand, if the bobbin thread is too thick, it can cause the fabric to pucker and not lie flat. This is because there is too much tension created by the thickness of the thread beneath the fabric.
  • Another factor to consider is the type of sewing machine you’re using. Many newer sewing machines are designed to work best with bobbin thread that is the same weight as the top thread. If your machine does not have the option to adjust the tension, it may be best to stick with the same thread weight for the top and bobbin.
thread for sewing leather
nylon thread for sewing leather

Three Solutions

  • To ensure that you are using the right size of bobbin thread, it is essential to check your sewing machine manual. Your machine’s manual will give you guidelines on the type of thread to use for both the top and bobbin threads. You can also experiment with different thread sizes and types to see what works best for your specific project.
  • When selecting a thread size for your bobbin, you should also consider the type of fabric you will be sewing. If you’re sewing lightweight fabrics, choosing a finer bobbin thread is ideal to prevent puckering and ensure a smooth stitch. In contrast, sewing heavier fabrics like denim or canvas will require a thicker bobbin thread to help hold the seams securely.
  • When winding the bobbin with thread, it’s essential to follow the manufacturer’s instructions. Using too much thread on the bobbin or under-winding it can create tension issues, which can cause uneven stitches. So, it’s vital to wind the bobbin correctly and ensure it’s the correct size and tension.


Using a smaller thread for the bobbin can improve your stitching quality. It helps create less bulk and results in flatter, smoother stitches. However, before using a smaller thread for the bobbin, you should check your sewing machine manual to ensure that it is compatible with it. Additionally, you should consider the type of fabric you’re using and experiment with different thread sizes and types to achieve the best results. Properly winding the bobbin with the correct tension and amount of thread is also essential to avoid tension issues and uneven stitches.