How to Calculate the Number of Beads Needed For A Project
Determining how many beads are needed for your project is actually quite easy. Since most beads are measured in millimeters you will first need to convert the length of your bracelet or necklace from inches to millimeters. (1 inch = Approximately 25.4mm)
To start, simply multiply 25.4 by the length in inches of the finished bracelet or necklace (excluding the clasp). For example, for a 18 inch necklace, calculate 18 x 25.4mm = 457.2mm.
Now, divide the total length in millimeters (in the example: 457.2mm), by the diameter of the beads to be used (let's use 8mm). The result will be your number of beads. In the example, 457.2mm divided by 8mm = 57.15 beads.
The chart below is a quick guide to the number of beads needed for common bracelet & necklace lengths. For 16"- 32" lengths I have rounded up.