The correct way to measure beads is to use a tool that is designed specifically for this purpose. The tool is known as a sliding bead gauge. The way that it works is it contains a ruler and a clamping jaw that grips onto the bead being measured. The upper jaw stays in place, while the bottom jaw of the ruler slides up and down.
The jaws of the special measuring tool can be opened and then pressed together lightly to correctly give you a measurement of a bead. Most beads are measuring in millimeters, altogether there are some gauges that will help you measure your beads in millimeters as well as inches. Most bead stores that sell beads will also sell these measuring tools.
1. The first thing you are going to do when employing the use of this tool is loosen the screw on the tool to open the jaws of the measuring device up. You may also compress the button that is located on the edge of the tool to force it to open.
2. Place one bead that you will be measuring inside of the open jaws of the ruler. One edge of the bead should touch the stationary portion of the tool that does not move. The side touching the still portion of the ruler is normally the side of the bead that contains the threading hole.
3. Make sure the bottom section of the ruler is tight and clamped down on the opposing side of the bead that is being measured.
4. The number on the ruler that shows where the flat portion of the bottom jaw of the ruler meets with the bead is going to be your measurement.
If you do not have one of these special tools available, an alternate way to measure beads is with a basic ruler. However, the measurements you will receive from measuring your beads with a ruler are not always accurate.