Commonly used sewing thread sizes are all-purpose thread and polyester jeans thread. Sewing machine users should pair these threads with specific sizes of needles. All-purpose cotton thread commonly goes with an 80/12 size machine needle.
This combo is appropriate for woven cottons and knits. Polyester jeans thread typically goes with a heavier 100/16 needle. This thread is heavier than the all-purpose version, and the needle is sturdy enough to pierce thick denim fabric. The thread comes in standard gold and blue-gray colors.
In addition to being the correct thickness, threads should be made of the same substance as the fabric, if possible. Cotton threads go with cotton material, and polyester thread matches synthetic fibers best.