The Dimension tool will dimension arcs just fine. You can use inferencing to draw a radius to the center if needed or you could use Arc Center Point Finder to place a guidepoint at the center. [image: PUuy_Screenshot-2_27_20248_38_31AM.png] If you were to update to the current version of SketchUp there's a native feature for placing a guidepoint at the center of an arc.