Bree123

Typically thread manufacturers will tell you what size needle to use on their websites. It's entirely dependent on the thread weight, fiber & ply. That said, you then need to have an idea of what weight of thread that is appropriate for what you're sewing.

For piecing quilters cotton or flannel, you generally want to work with a 50wt thread. I buy Aurifil 50wt/2 ply cotton thread & use a size 70/10 Microtex needle for piecing. I have used the same for quilting, but I now typically prefer to use Aurifil 40wt thread & I switch to a size 80/12 needle -- either Microtex or Quilting -- for that. If I really want a particular design to show up a lot in my quilting, I use 28wt thread & will then use a size 90/14 Top Stitch needle (that's also usually the ideal thread/needle for making Jeans quilts). When I do microquilting designs or am piecing with silk or linen, I switch to a 100wt silk thread & then use a size 60/8 Microtex needle.

If you are not accustomed to doing FMQ, I would strongly recommend a Quilting needle to start with. Quilting needles are designed to take curves well. They have a rounded tip that will reduce the likelihood of fraying your fabric while doing FMQ.

PS -- If you prefer, you can use a 90/14 Top Stitch needle for everything. It will sew through anything you could possibly put on your machine. The only issue is that it makes the largest holes. If you aren't using a heavy weight thread, the holes will be larger than the thread. They do shrink up some in the wash, but there will always be a tiny gap between thread & holes so I wouldn't recommend doing that either for competition quilts or heirloom quilts.