How to Add Seam Allowance in Affinity Designer

Adding seam allowance in Affinity Designer is quick and easy! After this tutorial, you will be able to increase the seam allowance on any pattern or add seam allowance to a pattern that doesn’t have any.

Projector files work best, but A0 files will work too!

If you are just joining these tutorials, I recommend at least a basic understanding of the tools in Affinity Designer. Check out Affinity Designer 101 and Affinity Designer 102 for more details!

Step 1: Open Pattern and Select Pattern Piece

Open a pattern in Affinity Designer. If the pattern is “locked” and requires a password, remember to run it through PDF Stitcher first!

Prepare the pattern by unfolding, grouping, and making any other adjustments to the pattern piece that you need to. Make sure to change the document to work in the correct units (cm or in).

This can be done in “Document Settings” or on the top left-hand corner of the canvas. Just right click on the units to and select centimeters or inches.

Make sure to only select one size layer at a time. Also, deselect any text or extraneous layers that you do not need.

Select the pattern piece that you will be working on. It’s best to work with one pattern piece at a time.

(Optional Step): Duplicate Pattern Piece

 Duplicate the pattern piece by pressing CTRL + J. This will allow you to see the original pattern lines once you are done and can be deleted or left intact.

Step 2: Using the Contour Tool

With the pattern piece selected, choose the contour tool from the left toolbox. Enter the following settings:

Radius: 0.5 (Type in the number of seam allowance that you want to add using decimal form for whatever unit you are using.)

Contour Type: Miter

Fill: Force Closed

Step 3: Bake Appearance

Now that the shape has seam allowance added, it will still show where the original shape was with an “outline” around it. You will be unable to modify any nodes.

To resolve this, click the “Bake appearance” and it will all be merged into one.

You will now be able to modify the nodes if you choose.

This will also help you to “clean up” any stray pattern marking lines.

Label your pattern!

Since you changed the seam allowance to the pattern, don’t forget to make note of it. Use the text box to state what the new seam allowance is so it can be sewed up correctly!

How to Remove the Fold Line in Seam Allowance

Sometimes when you contour on a pattern piece with a fold line you get a funky box in the middle around the fold line.

If you don’t want the box, then you need to remove the fold line before adding seam allowance.

This can be done using the “Node” tool (A). Break the curves where the fold lines meet the pattern edges. This may have to be done several times if there is more than one “line” on top of each other.

Next, use shift and click to select the nodes across the top of the pattern and choose “join curves”.

Repeat for the bottom.

You should now be able to delete the middle fold line.

How to Add a Center Fold Line

If you removed a fold line before adding seam allowance, it is quick to add a single fold line back into the pattern.

Use the pen tool (P) and select a point in about the center of the top of the pattern piece. While holding shift, draw a straight line down to the bottom of the pattern. Push “enter” for the line to complete.

Next, you will make sure the line is centered in the middle of the pattern piece.

Use shift and click on the line you drew and the pattern.

Go to the align menu in the top toolbar and choose “align center”. Tada! The line is now in the exact center of the pattern!

Fixing Cut Lines for Shorts and Sleeves

When using the contour tool, the cut lines for short options do not always transfer over well.

You can use the node tool to add nodes and extend these lines.

Duplicate the original curve or line to match. Then, using the Node tool (A).

Take the end nodes and extend them to the new seam allowance. Adjust the curves using the round points attached to the node.

You Did It!

Now you know how to add seam allowance in Affinity Designer! Way to go! If you liked this tutorial, please consider subscribing to my social channels and sharing it with your friends!

Thank you for joining me!