How Do You Determine the Right Seed Bead Size?

If you are a bead weaver, you likely know what seed beads are and have used them a few times. You most likely also know that seed beads come in a wide range of types and sizes and that sometimes, determining which ones would suit your exact beading needs could get a little confusing.

Since your choice of beads largely influences the look of your finished product, it is important to know how to choose them, especially regarding their sizes. In this article, we’ll review seed beads sizes and provide tips to help you determine the perfect seed bead size.

What Are Seed Beads?

Also known as rocailles, seed beads are uniformly-shaped, small, seed-like beads, hence the name. These beads are typically made of glass, with a few coming in metal form. Their sizes vary from less than 1 millilitre to several millilitres.

The most common seed beads are Japanese Cylinder Beads, Japanese Seed Beads and Czech Seed Beads. These beads are great for embroidery, off-loom bead weaving, and other beading projects. They are easy to use and usually give a great finish; however, you must get it right with sizing to use them efficiently.

Are Seed Bead Sizes Consistent?

At first, seed beads came in one standard size, and it was called “aught.” However, as more and more seed beads were produced, they began to vary in size. Today, aught is the unit of measurement for seed beads, and it can be indicated in any of the following ways:

  • As a number with the word “size” in front of it, for example, size 6
  • As a number followed by the symbol of a degree, for example, 6°
  • As a number followed by a slash and a zero (/0), for example, 6/0. This method is the most commonly used.

Since there are several seed beads brands and types, the sizes in millimetres of different seed beads are prone to minute differences, depending on some factors, including:

  • The shape of the seed bead. For instance, Toho seed beads are usually rounder than Miyuki Delica, which tend to be slender in shape
  • The manufacturing process used in making the seed beads, including coatings and finishings

If you are experiencing some confusion about the actual size of your seed beads, here is the different seed beads size chart at Bluestreak that you can reference. This chart contains a breakdown of each seed bead size. The categories of this breakdown are:

  • Seed bead size in aught sizes
  • Seed bead size in millimetres
  • Seed bead size tolerance in millimetres
  • Minimum diameter of holes, varying based on opaque and transparent colours
  • Approximate pieces of bead per kg

This breakdown is important to help you know the real size of your seed beads and what needle size and thread to use with each bead size. Using a needle size that is too small can cause your needles to bend, while those that are too large can be difficult to manoeuvre.

Note that if seed size uniformity is important to you, then it is advisable to stick to just one seed bead brand.

Determining the Right Seed Bead Size

Seed bead sizes range from 1/0 to 15/0, and you’ll rarely see any seed bead that exceeds these sizes. However, some of the most common seed bead sizes today are 15/0, 11/0, 8/0 and 6/0.

Here, it could get confusing: the smaller the size number, the larger the bead size. For instance, a 15/0 seed bead is smaller than a 6/0 seed bead. How, you ask? Let’s explain the maths.

Seed bead sizes are determined by the number of beads that can be lined next to each other, with their holes facing up in the space of an inch. The higher the number of beads lined, the smaller each of them is. So, if 8 seed beads make up an inch here, and 6 seed beads make up an inch there, the 6 seed beads are bigger than the 8 seed beads because they take up more space.


We understand that figuring out the right seed bead size for your beading project could get confusing, no matter your experience level. However, a careful study of the attached seed bead chart would pretty much explain anything that you’re missing. In addition, beyond the chart, refer to the details that we have provided in the article, and that should answer any questions that you may still have.