Determine Needle Size with Rhonda’s 80/40 Rule
The most popular thread used for all types of sewing, quilting, and crafting is a 40 weight thread. When using a 40 weight thread, use a size 80/12 needle. If using a thread finer than a 40 weight, such as a 50 weight, use a smaller needle size such as 70/10. Micro threads use needle size 65/9 or 60/8. Again, using a 40 weight thread with a 80/12 needle as a benchmark, if using a heavier thread, move up at least one needle size. If using a 30 weight thread, use a needle size 90/14 or larger.