Seed bead sizes can very with Manufacture
here is a general usage chart to help
a larger sharper copy of this is in our store's help pages
or many of our seed bead listings



15/0   -    1.5mm  -   0.059 inch   (tiny)
It takes about 350 beads to cover a square inch surface
working with these tiny beads can alow you to create intricate patterns and subtle color changes
we have received many request for these tiny beads and are just starting to carry Miyuki them in our store.
We picked Miyuki beads because of they are extremely uniform for such a tiny bead.

14/0   -    1.6mm  -   0.063 inch
13/0   -    1.7mm  -   0.067 inch
12/0   -    1.9mm  -   0.075 inch

11/0  -      2.1mm  -   0.083 inch
a standard used in brick and peyote stitch projects

10/0  -     2.3mm  -  0.090 inch
9/0    -     2.6mm   - 0.102 inch

sizes below are larger general use beads many come in specialty shapes large easy to work with holes
and blend well with larger beads in jewelry making
8/0   -     3.0mm   - 0.118 inch
7/0  -      3.4mm   - 0.134 inch
6/0  -      3.7mm   - 0.146 inch
5/0  -      4.5mm   - 0.177 inch

sizes below many times apply to Bugle Beads (tube beads in the seed bead family)
4/0  -   5.0mm     -  0.197 inch
3/0  -   5.5mm     -  0.216 inch
2/0  -   6.0mm    -   0.236 inch

For more how tos check out our other postings or our store help pages Rockinbead