To Convert Between Chain Dimensions, Baseline Dimensions and Ordinate Dimensions (AutoCAD Mechanical Toolset)

Click Home tabDimension panelPower Dimension drop-downMultiple Dimension. Find
In the Automatic Dimensioning dialog box, select the tab corresponding to the dimension type to convert to.
Select the Rearrange into a New Style check box.
Click OK.
Select the dimensions to convert (1).
Press Enter.
Depending on the chosen dimension type, specify the first dimension origin point (2).
Specify the dimension line location (3).
Press Enter to finish the command.