To measure a conveyor chain, you need to determine the pitch (distance between pin centers), roller diameter, roller width, plate thickness, plate height, pin diameter, and overall width. Use calipers to precisely measure each of these dimensions, being careful to capture any variations like differing inner and outer plate thicknesses or heights. Having accurate measurements of all these components allows you to properly identify the chain size by matching to manufacturer specifications or standards like ANSI, ISO, or DIN for replacement or design purposes.