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How to Grade a Pattern

No, not grade like what I do when my students turn in patterns! Grading a pattern is the process of sizing it up (or down). It sounds fairly intimidating, especially if you’ve ever seen any of the mysterious old-school tools for “assisting” in the process. (They’re a strange array of bars and levers, and I have absolutely no mortal clue what they’re meant to do or how they’re meant to do it.) Fortunately, there’s a quick and dirty way to grade a pattern…

You will need:

  • a pattern in the wrong size
  • a ruler
  • a scissors
  • a pencil
  • widthwise body measurements
  • lengthwise body measurements

Here’s some background theory: as anyone who has ever gained (or lost) a significant amount of weight knows, as the body ¬†grows (or shrinks) widthwise, it’s surface also gets longer (or shorter). That’s why your tshirts mysteriously get shorter (or longer) as you gain (or lose). Turns out it’s not the washer after all. ;)

So when you grade a pattern, you need to expand it both lengthwise and widthwise. It is worth noting that, as per my usual, I was doing this in a big bad hurry as part of a costuming emergency – the Vintage Vogue pattern I needed was only available in a small-y sort of size at the time I needed it, but it was faster to buy the pattern and grade it up than to draft the pattern (or drive to another JoAnn’s, for that matter). My point is that if you are reading this as one who is wise in the ways of pattern grading, this might look a bit slap-dash. Don’t worry. It was.

tools for pattern grading
The tools you will need: your pattern pieces, rulers, and a pencil. Well, Sharpie, in my case.
horizontal cutting lines marked
Start by marking horizontal lines on the pattern. You want the lines for the front and back of the pattern to line up.
mark as cutting lines
These are going to be cutting lines, so I mark them. (Also, I really like drawing the little scissors.)
vertical lines
You will need vertical cutting lines as well. Quick trick: use a clear gridded ruler to keep a longer ruler perpendicular to your original horizontal lines

But wait! How many lines do I need? Where do they go? As with so many things, the answer is a firm “it depends”.

The more curve to your pieces, the more you want to divide them. If I was grading a rectangular skirt piece, I could cut it into four pieces and spread them without losing any of the information in the pattern. With something more complex, like this bodice, I want my pieces to be small enough to let me distribute changes evenly along the curves without losing the general shape and proportions of the pattern piece. I personally don’t want to work with pieces that are smaller than 3″. Nothing scientific there; it’s just annoying. I don’t want lines that go right through corners, either. The corner is an important piece of information.

alignment lines
Once I’ve established my cutting grid, I add horizontal and vertical alignment guidelines to my pieces.
cutting the pieces
I can now cut my pieces apart on the cutting lines….
pieces laid out
…and lay them out with space between, using my alignment guides (and a ruler) to keep everything straight.

You may notice that I am doing this directly on my fashion fabric. Unless you’re stupidly overconfident and positive that you will never need this new size again, I’d recommend doing this on paper first to make a new pattern.

So, wait, I hear you ask, how do you know how far apart to spread the pieces?

Good question.

Measure the pattern piece (subtracting the seam allowances). Subtract this from your target measurements. Divide this amount by the number of cutting lines you’re using. For example, if I want to increase by 1 1/2″, and I have three cutting lines, I spread by 1/2″. When in doubt, go a hair large – it’s way easier to tailor down in size than up in size.

final shapes
Here’s the deal: you want the curves to be smooth, which means that sometimes you will deviate from the edges marked on the original pieces (mostly at corners). I’ve left the final graded pieces under the original tissue pieces so you can look at the difference between the marked black lines on the pattern and the cut pieces.

Technically, this process of making your curves nice and pretty is called truing, and should be done on paper with a french curve and/or a ruler rather than on fabric with a scissors. Um…. I have no excuses for my behavior. I just figured I should take the pictures while I was actually doing it, rather than wait for a time when I had time to do it right. “Having time” is not currently one of my strong suits.

And, oddly, that’s about it. People get all spaztastic about the idea of changing the size of a pattern radically, but at the most basic level, you’re just cutting the piece up on a grid and adding space.


  1. Kirstine
    Kirstine April 8, 2013

    I have nominated you for an inspiring blogger award

  2. Jaquelinne
    Jaquelinne April 11, 2013

    Can I just say THANK YOU? I’ve ready so many articles on grading, and they don’t sink in. I can wrap my head around this. Mercy buckets!

  3. Vince
    Vince July 10, 2014

    Thank you so much for taking the time to post this, and making it easy to understand. I’ve looked at countless other tutorials and they all make it much more difficult than it needs to be.

  4. Laurie
    Laurie December 6, 2016

    Thank you. I finally get it.

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