AutoCAD Field is a great tool for AutoCAD 2005 or later. Fields are a really nice addition that give you quick access to various types of information via TEXT, MTEXT or an Attribute.
You can calculate the length of a single AutoCAD object (Line, Circle, Polyline etc.) with AutoCAD Object Field. But you can’t calculate the length of multiple AutoCAD objects. AutoField provides an additional field to do it.
1. Use the Insert menu or right click to choose Insert ->Field.
2. Select “AF Objects Length” in the left panel of the Field dialog.
3. Select the objects (supports LINE, POLYLINE, CIRCLE, ARC) to calculate.
4. Click OK to insert the field to the drawing.