THUA (or now, TUA) class: Introduction to clothing pattern alterations

I had hoped to teach the following class at Quad War 2015 at the end of August, but unfortunately I wasn’t able to find a ride up to the War, so couldn’t attend. Apparently there was some interest in taking the class from those who were per-registering, so the organizer asked me to make my notes available so another instructor who was able to attend could teach instead.

Here are my notes for anyone attending… If you have questions, please speak to the teacher teaching the class… there’s a lot here that I was going to show in-person rather than just rely on hand-outs.

*bummed I can’t attend*



Introduction to clothing pattern alterations

Have a sewing pattern but it needs some tweaks? I’ll introduce you to some basic concepts for altering a pattern for fit or style. Due to time constraints, you’ll learn basic concepts, but will not have the opportunity to alter your personal patterns in-class.

With Drífa at lækjamoti

Maximum 8 students

Cost: $2.00/person to cover cost of printing

Supplies: Please bring a pair of scissors for cutting paper, a pencil with eraser, notebook, & chair.

Paper hand out provided, digital copy available online.


If you are creating clothing more complicated than a t-tunic, you probably are using a pattern. This might be something you’ve scaled-up from a costuming book, or more likely, a commercial pattern you’ve purchased. (If you’ve drafted a pattern, this workshop is probably too basic for you 😉 )

In many cases, commercial patterns won’t be quite what you are looking for – for instance there might be darts when you know darts were probably not used in your period, they might feature a rounded neck when you want a square neckline, or the waist might sit at a current fashionable waist instead of a raised/dropped waist that was more common for your period.

I’ll give you a starting place to feel more comfortable altering your patterns to better suit you, and the style you hope to create.

Although I’ll be using women’s patterns for my demonstration, the same techniques are used for menswear and children’s wear.

Workshop preparation steps

You should have:

  • A basic bodice block miniature (front only)
  • A basic skirt block miniature (front and back)
  • Light card stock, glue stick (optional, this will just make tracing easier)
  • Paper
  • Pencil, eraser, ruler or straight edge
  • Scissors suitable for paper
  • Clear tape

Glue the draft miniatures to the card stock, then cut them out so you have something to trace around. If you’re running a bit late, you can skip this step, though it makes tracing your block faster and easier.

Step 1 – remove the seam allowance

bodice block

Bodice block portion from

This might seem like a fussy, annoying step, but it will help you from getting confused about where seam allowances are and aren’t on your pattern after you alter it. If your pattern includes seam allowances (not all do, but most commercial patterns do) look at your pattern (or pattern instructions) to find out how much seam allowance has been added in for each seam, and use a gridded ruler to draw the stitching line, and then trim your pattern. You can re-add seam allowances where needed after you’ve made your alterations.

If you think you’ll want to use your pattern again, you can also trace it off onto pattern paper, and remove the seam allowances on this copy instead. (Lots of people don’t love the idea of cutting into their patterns, and trace them off instead to allow for easier alterations.)

Personally … I generally don’t add any seam allowances to my patterns, but rather cut them out “by eye” so I can add the amount of seam allowance I want based on my seam finishing, the garment I’m making, and the fabric I’m using.

Step 2 – determine your new style line

If you’re changing the style of the pattern, you’ll need to identify where you’ll be making alterations. Are you altering the neckline? The bust darts? Dropping the waist?

Determine what elements are vital to the fit of your pattern – if you have a pattern that has the right bust, waist, and hip circumference, you know you can’t reduce these – but you can MOVE them. Most modern patterns accomplish fit through seams and darts. Their importance to fit is vital, but their location is style.

Step 2 a – liberally mark or transfer your grainlines

Your pattern probably has the grain line marked once, but depending on where you’re altering your pattern, you may lose this marking. Transfer it to an area that will not be cut off. If unsure, typically you want to align your grainline with the centre front, centre back, or have it run perpendicular to the waist line.

But consider… different styles do hang in different ways. Take a circle skirt for instance. With the grainline oriented with centre front, side seam, or the middle of the circle-skirt panel, the circle skirt will hang in different ways. This is a style choice you can make!

Circle Skirt layout changes the way the skirt hangs – from Pinterest

Step 3 – Draw your new style line.. and begin the alteration!

Start with pencil, and draw your new style line.

For this workshop, we’ll be altering a bodice with a waist and bust dart into a bodice with a shoulder-origin princess seam.

  1. Trace/outline your block onto some of your paper. We’ll use this paper for several items if there’s time, so trace it in a corner.
  2. Find the bust-point. On your mini-sloper/bodice block this is marked with an asterisk. You can ‘estimate’ where this is on your traced block, since we’re not working with tissue paper.
  3. Re-draw the ‘legs’ of your bust darts, from the waist up to the bust-point, and from the side-seam to the bust point.
  4. Draw a line from the bust point up to the shoulder seam (in the middle of the seam)
  5. Carefully cut out your bodice, cutting out the triangles that make up the two darts.
  6. Cut the line you’ve drawn from bust point to shoulder, through the shoulder seam line, and through the bust point. You now likely have three pattern pieces.
  7. Close the bust dart that originated from the side seam with a small piece of tape
  8. You now have a centre-front front piece and a side-front front bodice piece.

When you’d use these patterns to sew with, you’d smooth the points and angles using a curved ruler. This will make it easier to sew, as well as creating a nice curve over the bust, rather than a sharp point. (Unless you want to do the 1950s bullet-bra look!)

If there’s time, let’s try another alteration!

This time, we’ll use our skirt block. Divide the skirt block into two pieces, a front and a back by cutting up the side seam. We’ll be making a fuller skirt, and closing the waist dart.

  1. Trace/outline the front of the skirt onto your paper.
  2. Draw a line from the tip of your waist dart to the hem of your skirt
  3. Cut out your skirt pattern piece
  4. Cut up the line you’ve drawn, to one side of the skirt dart.
  5. Layer the left and right halves of the skirt on top of one another, closing the dart.
  6. To better see what this might look like, glue your pattern onto another piece of paper, and use a curved ruler to connect the two edges of your skirt.
  7. You now have a pattern for a skirt front with no waist dart, and additional flare to the hem.

Now… experiment! Where else could you put a bodice dart? What else could you do to add more flare to a skirt and make a fuller skirt? How could you combine a well-fitting bodice with a well-fitting skirt?

Step 4 – smooth your lines, and replace your seam allowances

Now that your alteration is complete, you’ll want to re-trace your pattern (or glue/tape it onto more paper) and smooth your lines. You’ll also want to make sure that those “vital parts” still line up…. if you altered the shoulder seam on the front of your bodice in any way, is it still the same size as the shoulder seam at the back of your bodice?

If you altered your neckline in the front, does it meet up with the neckline at the back nicely with a smooth line? This is called “truing” your pattern. If you have darts in your finished bodice, you’ll also want to fold your pattern paper to establish the outside shape of the fabric you’ll need for that dart. Once you’ve made these minor tweaks (hopefully minor!) you can then add back on your seam allowances if you need them, confirm your grain lines, and cut out your fabric to test out your new pattern!


I get my favourite pattern tracing paper from the Great Notion Supply in Abbotsford & Surrey. You can also use plain newsprint, wrapping paper, etc.

Gridded and curved rulers are a valuable asset. You can find them in imperial and metric, through quilting shops, art supply shops (usually in the drafting section) and stationary stores.

Hand out

I’ve loaded up the hand-out here which includes the slopers you’ll need for this class.
Anyone teaching an Ithra class is free to use this hand-out and the slopers, as long as my name/website remains on the publication. I’d also ask that you leave a comment below letting me know where and when you teach this class and in which Kingdom/Barony/Shire!
This hand-out and slopers are NOT available for anyone teaching for-profit.

Introduction to clothing pattern alterations – PF hand-out

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