About Thread, Needle and Bobbin Sizes

If 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 are some guidelines

• Use size 46 and 69 for lightweight interior fabrics and leathers. You an use either a home or commercial machine.

• Use size 92 and 138 for middleweight fabrics and leathers used with car and bike seats. You need a commercial sewing machine for this kind of work

• Use sizes 207 and higher for things like high-end seats and dashboards. You need a heavy duty ( e.g. walking foot) machine push the thread through the leather.

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 sizes 46 or 69 for seams you can use sizes 69 or 92 for decorative stitching.  Here are other ways to make your stitches pop:

• Use contrasting leather / fabric 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 138 your bobbin thread should be size 92.

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.