Convert objects to Polyline and Spline in AutoCAD

At times you may need to convert the line to polyline or polyline to a spline and sometimes Spline to a Polyline. You can do all of these tasks using few simple commands, let’s see how it can be done.

Converting Line to Polyline

You can convert Line to Polyline using “Polyline Edit” tool of AutoCAD, using this tool you can also convert an arc or spline into a polyline. However, you can’t convert circle, ellipse and elliptical arc into a polyline using this tool.

Type PE on the command line and press Enter to start polyline edit command, the command line will prompt you to select objects for making changes. Click on the object which you want to change to polyline, you can also select multiple objects by selecting Multiple from the command prompt.

Convert to polyline and spline

Once you have made selection a new prompt will appear on the command line stating that selected object is not a polyline do you want to convert it as shown in the image below. Type Y and press enter twice to convert the object into a polyline and exit this command.

convert line to polyline

Converting Polyline to true spline

To convert a polyline into true spline type PE and press enter, then select polyline which you want to convert and select spline from prompt appearing on the command line. Press enter to exit polyline edit command.

convert polyline to spline

This will convert your polyline into a “polyline spline” which looks like a spline but inherits properties of the 2D polyline.

To convert it into true spline type SPE on the command line and press Enter. This will start Spline Edit command, select “polyline spline” from drawing area and press Enter. The 2D polyline will be converted into a true spline and it will also inherit all the properties of a spline.

Converting Spline to Polyline

To convert a Spline into a polyline type PE on the command line press enter then select the spline from drawing area and press enter again. The spline will be converted into a polyline.

Alternatively, you can also use Spline Edit (SPE) command to convert a true spline into a polyline by simply selecting “Convert to Polyline” option from the command line options.

convert spline to polyline

In this case when the command prompts you to specify the precision enter the default value 10 or any other value which you like. Higher the value of precision more accurate will be the converted polyline with respect to the spline but it will also create a dense polyline.

The value of precision can be set between 0 and 99.

Thanks, R.K McSwain for suggesting this tip, see more tips from him on  Cadpanacea. If you have questions related to this tip let me know in comments below.

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About the Author:

I am a mechanical engineer and I have worked with Design, Manufacturing and Training industries but now SourceCAD is my full-time work and I use it to train students all over the world. I also train corporate clients and help them develop the skill set of their workforce. I am Autodesk AutoCAD Certified Professional and an Autodesk expert elite member. I am a regular contributor of AUGI World magazine and apart from SourceCAD I also develop AutoCAD video courses for Pluralsight and other E-Learning businesses.


  1. Mei January 31, 2018 at 6:25 am - Reply

    Good morning.
    How to convert many polyline to spline at once without select it one by one?

    • Jaiprakash Pandey February 5, 2018 at 11:54 pm - Reply

      A LISP routine would be required to do this and unfortunately, I am not good with LISP 🙁

  2. Wallace Phillips January 14, 2016 at 2:09 am - Reply

    Regarding this prompt:

    Object selected is not a polyline
    Do you want to turn it into one?

    If you want to make the line into a polyline automatically and bypass the prompt, set the PEDITACCEPT variable to 1

    • Jaiprakash Pandey January 14, 2016 at 11:07 am - Reply

      Thanks for the tip Wallace

  3. Momcilo January 11, 2016 at 5:36 pm - Reply


    • Jaiprakash Pandey January 11, 2016 at 5:53 pm - Reply

      Thanks Momcilo

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