Thread weight (wt) describes how fine or heavy a thread is. Confusingly, a higher number means a finer thread. This chart maps weights to uses.
| Thread weight | Best for |
|---|---|
| 12 wt | Heavy topstitching, decorative |
| 28 wt | Bold quilting, embroidery |
| 40 wt | Machine embroidery, quilting |
| 50 wt | Piecing, general sewing |
| 60 wt | Applique, fine detail |
| 80 wt | Bobbin work, lace |
Higher number, finer thread. The weight number is roughly inverse: 50 wt is an everyday all-rounder, while 12 wt is thick and showy. Match thread weight to needle size.
See the Thread Weight Comparison and the Seam Allowance Calculator.