A metric screw and bolt thread chart can be found at FastenerMart.com. Unlike inch-sized screws and bolts, metric screw sizes are preceded by an "M," and the dimensions are listed in metric units.
Metric screws and bolts are sized using three main factors: The screw diameter, the thread pitch and the screw length. In addition, screws and bolts are designated as "coarse" or "fine" thread, which means that the threads are larger or smaller, respectively. The diameter of the screw is simply the diameter of the screw shaft itself, not including the head. The pitch is the distance between the threads on a screw (larger on a coarse thread screw). The length is the total length of the shaft of the screw.