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.

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.

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.

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.