About Thread, Needle and Bobbin Sizes

ff you are sewing seams the thread's thickness depends on the material's thickness. An undersized thread can result in stitches breaking; an oversized thread leads to situations where the leather rips at the seams. Here is what happens as thread size increases:

• Thread strength increases

• Thread diameter increases

• Sewing machine power increases. Commercial machines can handle up to size 277; heavy duty (e.g. walking foot) machines are need for heavier sizes.

• Needle size increases.

• Yards of thread per pound decreases.

With decorative stitching look is everything - you want the stitching to be the focal point and thread strength does not matter. As a rule, decorative stitching thread can be one size heavier than thread used to sew seams. For example, if you use size 138  for seams you can use size 207 for decorative stitching.  Here are other ways to make your stitches pop:

• Use contrasting leather and thread colors.

• Use large stitches.

• Use multiple, closely spaced rows of small stitches.

Bobbins - Your bobbin thread should be one size smaller than your topstitch thread. For example, if your topstitch thread is size 207 your bobbin thread should be size 138.

Needle and Thread Size - Needle size increases as thread size increases. Our Needle and Thread Size Chart shows needle sizes for different kinds of thread and thread thicknesses.