Pattern adjustments can be intimidating—but they don’t have to be. I adore step-by-step tutorials on making pattern alterations (they can save so much time!), but I think it’s important to understand why they work, not just how to do the steps. Without understanding, we get stuck searching for the perfect tutorial (that might not exist) instead of confidently making the changes we need for our unique body.
But fear not! There’s no reason you can’t come up with your own adjustments once you understand the process. And the process starts here.
Here are the first questions to think about:
- Where do I need more or less fabric?
- What elements of the garment must stay the same?
- What areas must be on the straight grain?
- What seam lines need to be longer or shorter?
- How much precision do I need?
1. Where do you need more or less fabric?
This one is pretty straightforward—it’s the reason you’re making a pattern alteration in the first place.
Sometimes you need more material in several areas, sometimes just one. Or you need more material in one place, but less right beside it. Make a list of the areas where you need more room, and the ones that need to be smaller, including the approximate amount of each adjustment.
I like to mark these areas on tiny, rough sketches of each pattern piece.
In this example, we need more room in the shoulder, but less in the waist.
I’m using arrows in this example, but usually I’ll just scribble over the areas I need to change. It only has to have meaning for you!
2. What elements must stay the same?
Whether it’s seam lines, angles, darts, or curves, it’s important to know which areas you don’t want to mess with before you figure out how to make the changes you need.
Seam Lines
Some parts of the garment are probably already the right size. Maybe you need a full bust adjustment, but the front torso length is already correct. That means you’ll have to modify the most common full bust adjustment technique to maintain the length. Note those seams that can’t change.
Darts
If the darts are exactly the right size, pointing to exactly the right place, don’t mess with them! You can work around it. I promise.
In this example, the front length, armhole and dart all need to remain (mostly) unchanged while adding width to the shoulder and taking in the waist.
Angles
Ah, angles. So important, and so little discussed in sewing. Like everything else, some matter, some don’t. For example, you might need more width in your shoulders, but the shoulder angle needs to stay the same. This might require you to lower the armhole, since your shoulder point will end up lower than the pattern anticipates.
To keep the shoulder angle when changing the width, the armhole either changes shape or ends up lower.
See my Concord T-Shirt review for specifics on this alteration.
Curves
Some curves are more finicky than others—for example, armholes. If you’re making a bust or shoulder adjustment, you may have to be very careful to keep the armscye the same length and shape. Or maybe you need to make a full seat adjustment, but the crotch curve fits you perfectly and you need to keep that exactly the same.
It’s all possible as long as you know the limits of what you can alter. I mean, there are no limits, but you might want to keep some parts the same.
3. What areas must be on the straight grain?
These are typically the areas where you want the least stretch and are often, though not always, the larger center areas of major pattern pieces. Ignoring the straight grain in these areas will make the garment hang strangely as it stretches with wear. Other areas (like armholes) either use the bias stretch to their advantage, or (like many necklines) get staystitched in place.
This usually won’t change much from the original pattern, but it’s worth keeping in mind when you plan your changes.
The purple arrow shows the straight grain.
Keeping the center front on the straight grain will help the garment not stretch longer when worn.
4. What seam lines need to be longer or shorter?
The order here is important: First know where you want changes, then know where those changes cannot occur. What’s left is to figure out how to get the changes you want without messing with the elements you like!
This is closely related to the first question, because if you need less fabric in the shoulders, the shoulder seam probably needs to be shorter. But maybe you have too much fabric in the shoulders AND the neck is too wide, in which case the shoulder se/ams can stay the same and you can just take width from the neck area. It’s going to be different for everyone, so sketching it out really helps.
This is where we figure out how to make the changes we need.
Knowing where we want more or less material and what needs to stay the same, we can figure out what seam lines to change to make it happen.
Black lines in this image may or may not change during the adjustment.
5. How much precision do I need?
This points to my philosophy of not wasting time making a pattern more precise than we can sew it. How precise we need to be depends on a number of factors, like the style of the finished garment and the fabric we use. For less stable knits, we usually have more flexibility than with a woven garment. If it’s a gathered sleeve head, you likely have a bit of flexibility in the armscye shaping and length. If it’s a stiff fabric in a fitted silhouette, well, then those 1/16 inches might really matter.
There are many factors that play into precision—stitching is just one.
You can see here how the stitching precision might affect your alteration decisions.
Next steps
Once you have these answers, make sure the tutorial you’re following (or the method you’re creating!) match what you know you need. If it doesn’t, consider if it’s the right tutorial for you, or if it needs some modifications for your particular situation. It’s all about volume, and even if you don’t want to calculate exact numbers (even I rarely bother, and as you know, I love the math), your alterations should always make sense to you.
Your alterations should always make sense to you.
I like to sketch the pattern pieces I need to alter, and color code the lines I need to change. This is a convenient sanity check for me before I work with the full sized pattern pieces. PDF patterns often have a 1-page layout showing all the pieces that you can print off and use! Alternately, just make rough sketches—it doesn’t have to be exact.
Because I’m a huge proponent of experimenting, I am firmly on the side of tracing all my pattern pieces, and leaving the original alone. Then if I mess up my adjustments, I can just go back to the original. It adds a step, but saves a lot of time in the end.
Do you have any questions or additional tips? Let me know in the comments!
Also, if you’re looking for an easy summary, check out the infographic below.
Good luck with those alterations!
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