How are Seed Beads Sized?
Round seed beads, cylinder beads and some other types of seed beads are sized according to numbers called aught sizes. When pronounced, people most often say the aught as zero, so eleven aught is pronounced eleven-oh (as in zero). When written, the aught may be indicated by a /0 or with what looks like a degree symbol.
The most common aught sizes you will find at bead shops and online are 15/0 (the smallest), followed by 11/0, 10/0, 8/0, and 6/0.
Size 6 is the largest seed bead and is often called an 'E' bead.
Here is a little background on why seed beads are sized this way. When seed beads were first being manufactured, the standard size bead was referred to as the “null” or “aught” bead. There is generally no agreement on how the sizes were developed, but it is believed that they were numbered according to how many beads could be lined up side by side (with the holes facing up!) in the space of one inch. Accordingly, the larger the number, the smaller the seed bead.
Regardless of the size of the beads, before starting your beading project, it can be helpful to sort through and take out any beads that may be larger or smaller than the rest. This is called culling your beads. Even in a batch of cylinder beads you will find a couple that are slightly wider or thinner than the rest. You can set these beads aside to use when making increases and decreases in your stitching.
Do All Beads Have Aught Sizes?
Round seed beads and Japanese cylinder beads both have aught sizes. It is also helpful to know that some other specialty seed beads such as hexagon beads, triangle beads and 3-cut beads are also sized using the aught system.
Many other types of small beads such as fringe beads, triangle beads, cubes and bugle beads do not necessarily hold to the aught sizing system. Bugle beads, for instance, are usually sized according to their length in millimeters and noted as a pound sign (#) followed by a number. Cubes and fringe beads are usually just labeled according to their size in millimeters, and triangle beads are either labeled with aught sizes or in millimeters, similar to the sizing system used for bugle beads.
Are All 11/0 Beads the Same Size?
With new companies making seed beads as well as new manufacturing techniques, seed bead sizes have changed over time. Consequently, seed beads produced today do not necessarily size up according to their aught number. There can also be slight variations in the size when beads are purchased from different manufacturers.
This is especially true since the beads shape can dictate the width of the bead, with cylinder beads being naturally more slender and even than round beads. Czech seed beads in particular, are rounded on the sides like a donut. They are typically not as tall as Japanese cylinder beads. Czech round seed beads are also flatter when compared to round Japanese beads which have a height similar to cylinder beads, but are wider around the middle to give them the round profile.
If you are in doubt about the actual size of your seed beads, download our free bead size chart that includes bead sizes in millimeters and aught sizes. Another way to picture the bead size is to stitch up a sample of the beading stitch you will be using. One of the most important aspects of bead sizing is to understand what type (manufacturer) of beads are called for in a design. Failure to use the same type may impact the overall look of your finished project.
When stitching with beads, it is also important to match the size needle and thread to the size seed beads you are using. A needle that is too small can bend easily while one that is too large can cause unnecessary wear on the thread or worse - cause the bead to break.
Edited by Lisa Yang