What is the Convert Entities Tool in SolidWorks?
Convert entities command in SolidWorks is basically used to make a replica of sketch entity or its dimensions in the same plane or another co-ordinate.
Why We Use the Convert Entities Command?
The word ‘entities’ refers to either sketch geometry or the edges of any e existing model. When using SolidWorks we are supposed to make complex designs. In order to save time, we need an option which can create the exact replica of a particular sketch entity, face, loop, sketch contour or edge. There is an option of offset entities tool with which we can do offset from entities previously used to make another feature. Whenever we are trying to make a sketch entity which resembles the geometry of our model, we use convert entities tool.
How to Use the Convert Entities Tool?
Now we are going to understand how to use this tool with an example. In order to explain this more clearly we have used an example in figure 1. In this figure you will see two things, a solid geometry called the boss extrude and a plane. We are using this to help us explain the convert entities sketch tool. The first thing we will do is to choose and create a boss extrude sketch based feature.

Figure 1. Showing reference plane and boss extrude geometry
We will select this plane here to sketch on. What we like to do here is to create the same shape as solid geometry here. We see three edges and an arc in the shape. We can use the line tool and the tangent arc tool to create this shape segment at a time we can do it this way but the convert entities tool is much better way to accomplish this.

Figure 2. Showing the exact same dimensions sketched on plane as that of object using convert entities tool.
Click on the convert entities icon on the sketch toolbar. To capture the contour geometry add this tomb stone shape, we can simply select the edges of the geometry that we would like to convert. We can do this by individually selecting each edge. Notice that the edges were selected are added to the entities to convert selection window. To remove an entity we can reselect in the graphics window, right click on it in the selection window and click on delete or clear selection to clear the entire window. Another way to select the geometry is to right click on the edge and choose select loop or we can simply select the face that contain the contour geometry.
We will press the green check to project the selected entities on to the sketch plane. The convert entities property manager is still active allowing us to select more entities to convert or if we did not select the entire outline of the tombstone, we could select the remaining edges without relaunching the command. We could press either the green check again or the red axis to exit the feature since there are no entries on the selection window. Not only is the geometry copied over but we noticed that the sketch segments all black or fully defined although we did not use any dimensions to constrain the sketch.

Figure 3. Showing that projection in the object will update the sketch in the reference plane.
The reason for this is that converted entities have a special geometric relationship called on edge. What this means is that the geometry will change an update based on any change that occurs to the geometry it is based on. As we mentioned the on edge relationship is special because it will change to always mimic the geometry it is based on. So if we change the shape of this tomb stone, notice that the sketch changes and updates as well. This is a very powerful parametric capability that we will expand on in much greater details.
How to Use Convert Entities in 3D Modeling?
Let’s take an example of the use of convert entities in 3D modelling. Click on the front plane. Make a rectangle and select extrude boss command to make some thickness.

Figure 4. Showing extruded geometry in normal plane and two circles at a distance.
We will draw two circles at some distance. As shown in the figure. Exit the sketch and go to reference geometry and create a reference plane from this face at some given distance.

Figure 5. Showing a reference plane at a distance from the extrude boss geometry.
Suppose we want to sketch these circles at the given reference plane and extrude it, for this we will select the plane and click on sketch option. Make it normal and choose the convert entities. Select both these circles. Exit the sketch and see the diagram in 3D, we now have circles on the reference plane. Extrude these circles by selecting extrude boss tool.

Figure 6. Showing the results of convert entities tool and extrude boss command.

Figure 7. Showing the final results.
Conclusion
This ‘convert entities’ tool allows the user to project the selected geometry from previous plane to the active plane without consuming time. Any changes made in the original plane, will be updated in the active reference plane.