There are several bead sizes, charm sizes, and measurements of how may beads can fit a string.  If you love making beads, it would be beneficial for you to know what are the standard sizes of beads and charms, and also in additional, how many will fit a string.  

Alphabet beads measure 12 mm in length,   with a 2.5 mm hole each.  “
Crystal Swarovski charms measure 11 x 14 mm on average.  

Apart from the standard size, Italian charms have small, medium, large and extra large sizes.  They have two unique kinds of charms, “Super Links” and “Double Links.” Their designs appear to be oversized. 

A Super Link is twice the standard size.  It has the same height, but looks like one piece which is long and horizontal.  The size may be said to be like two standard sizes which are linked together and appear as “one solid piece.”  Double Link Charms split in half, and are two charms hooked together which create a single design.  The size is two standard sizes combined together. 

Seed bead sizes are measured in an “international x/0 format,” and no one is actually sure what the number before 0 means, but it has been popularly believed that it is the number of beads which may fit one inch.  And so here goes the proportions.    6/o has a 3.3 mm measurement, 7/has a o 2.9 mm measurement,  8/o has a  2.5 mm measurement, 9/o has a 2.2 mm measurement,  10/o has a 2 mm measurement,  11/o has a 1.8 mm measurement, 12/o has a 1.7 mm measurement,  13/o has a 1.5 mm measurement,  14/o has a 1.4 mm  measurement, 15/o has a 1.3 mm measurement,  16/o has a 1.2 mm measurement,  18/o has a 1.1 mm measurement,  20/o has a 1 measurement, and 22/o has a 0.9 mm measurement. 

Just refer to a ruler for the size.  Here are charm sizes for babies, and children, as well as for adults.  For babies and children, sizes vary from three months to 12 years old.  For adults there are small, medium, large and extra large for bracelets.  For necklaces, there are two sizes, small and large.  As for the amounts of seed beads in a string, there are several for Czech seed beads.  These are called “seed beads” because of the way they are cut and shaped. They are also called “E Beads.”   6/0 seeds beads are larger than 11/0 seed beads, and are 4.0 to 4.4 mm wide, with nine beads per inch, or four beads per cm.  180 beds are expected per strand.  The hole is 1.2 – 1.4 mm, and are usually square, not round. A 1/0 bead s seed bead is one of the largest beads made, and measures 6.5 mm wide.  Five t to six beads may fit per inch, or two per cm.  That is about 100  -120 beds per strand.  It has a 1.72 hole size, and usually the holes are square and not round.