Shoulder width measurements to pattern adjustments: a complete guide for sewists

Did you know that pushing up your sleeves gives you more room in the shoulder? In most garments that I don’t make myself, I find myself pushing up my sleeves—even when I’m freezing—just because it’s more comfortable when my shoulders can move freely (shocking, right?). I would say that I spend a lot of time making broad shoulder adjustments to my patterns, but that’s no longer true. I do them so often it doesn’t take much time!

Since my narrower-shouldered friends complain of the same thing, only from too much material hindering their poor shoulders, I know I’m in good company. Sometimes it’s hard to tell exactly what is making you uncomfortable, however, so read on for how to know if you need to change the shoulder width on your patterns, and for two different methods of making narrow or broad shoulder pattern adjustments.

Already know what you want to do? Go straight to the adjustment tutorials.

How do you know if you have broad or narrow shoulders?

Because there are so many measurements, and each body is unique, there’s not a simple answer to this. A large bust could take up room in your clothes that should belong to your shoulders, and make your shoulders look broad when they’re actually average. An unusually thin neck could make your shoulders look long, when really it’s just your neck taking up less space.

To make it more complicated, shoulder width is relative to other measurements. So depending which measurement you judge against, your shoulders could be broad, narrow, or average. Your shoulders could be wide relative to your bust, but narrow relative to your hips.

But measurements are truth, so let’s get to it, and I’ll show how to use them in a bit!

Method 1: Measure an existing shirt/top/dress that fits well

The easiest is to take a perfectly fitting shirt and measure it…but, if you’re like me, you won’t have a shirt that fits well until you make it, and you need to know what alterations to make to create this perfect shirt, which requires the perfect shirt…and the circle has no end. But if you have this perfect shirt, go measure it and save yourself some time! Don’t worry, I’m sure you have other difficult measurements to spend your time figuring out.

Spread the shirt out on a flat surface with no wrinkles. It’s usually an easier measurement if you have the back facing up. Make sure the shirt is folded at the shoulder points (you may need to put it on to determine this if there’s not a shoulder seam). Measure from shoulder point to shoulder point.

To calculate body measurements (estimates, as this can vary by style):

• If it’s a woven shirt with no stretch, subtract about an inch if you can move well in it. More if you can move really well.
• Subtract half an inch if it looks good but you have a bit of trouble moving, or if it’s a stretchy woven fabric.
• If it’s a knit shirt, you can probably use the measurement as is.

Method 2: Taking shoulder measurements

If you don’t have a shirt that fits great, or just want another check, measuring your actual body is always a good idea. It helps to have someone to measure for you, but you can do it on your own.

Materials:

• flexible measuring tape
• quarter inch labels (or small pieces of tape)
• Sewing notebook & pencil (pens are for people who don’t make mistakes, which does not include me)

I like to wear a camisole for this (or just measure in my bra if there’s nobody around), so that nothing is shifting near where I want to take measurements.

Taking shoulder measurements with a helper

1. Put quarter inch labels at your shoulder points. You can find your shoulder points either by just visually deciding where you like the shoulder seam to hit, or by feeling for the edges of your shoulder bones, and placing the label right on the edge.
2. If you have a helper, have them measure between the dots, center to center, across both the front and back of your neck. This is much easier than the next method.

Taking your own shoulder measurements

If you don’t have a helper, or if you don’t trust your helper to be accurate, you’ll need a camera with a time delay and a tripod or pile of stuff to set it at the right height. Or have your helper take the pictures; your choice.

You’ll want the camera about neck or chin height, tilted down to see your shoulders. Hold the tape measure in both hands with your shoulders relaxed, so that it crosses both quarter inch labels. Don’t worry about where the tape measure crosses the dots, as long as it does and you can see both the tape measure and dots in the picture. Take several photos, trying to stay relaxed each time.

Look at the images and note the marking at the center of each label. For each picture, subtract the smaller number from the larger, then average the results (if one is way off, ignore that one).

With that, you have the most important shoulder measurement to determine if you need broad or narrow shoulder adjustments! Next, we add ease and compare it to patterns (or clothing).

Adding ease to shoulder measurements

For woven garments, you’ll also want to add ease (for knits, sometimes negative ease, though I prefer zero ease on knits). Here are some rules of thumb that I use (adjust to your preferences):

• For woven first-layer garments (shirts, blouses, whatever goes over your underwear): I like half to three quarters of an inch per shoulder (1–1.5 inches total). This depends on the style and whether there is some stretch to the fabric.
• For knit first-layer garments: I just use my base measurement, with no ease, 99% of the time. Some knits are sooo stretchy that even if you stabilize the shoulder seams (you always should), they may stretch at the neckline, requiring you to use negative ease. In this case, I never subtract more than a quarter inch per shoulder.
• For second-layer garments (sweaters, jackets, anything that goes over a shirt): I typically add half an inch per shoulder, depending on stretch, style, and what I want to wear underneath. You need more room because these garments have to fit over your first-layer garments. This is just the measurement I use most often, though—I use anything from a quarter inch to a full inch or more per shoulder. Study the garment, and use your best judgment.
• For third-layer garments (winter coats, capes, and anything that might go over a sweater/jacket): I add about 1.5 inches per shoulder OR MORE. Once you have that many layers, it gets harder to move well, and a bit of extra space in the shoulders makes such a difference.

Note: these ease measurements are just suggestions based on how I like garments to fit, and I play with them a lot depending on fabric, style, and my mood.

Determining if you need a shoulder width adjustment

Great, you have your measurements, and you’ve added your ease. Now what? Now we pick our pattern size based on whatever metric we like (bust or overbust, usually), and measure!

For shoulder measurements, it’s especially important to draw in your seam lines, since it will drastically change the measurement.

When you’re using a pattern that’s the whole front or back (as I like to do whenever possible), you’ll measure shoulder point to shoulder point. Compare this measurement to your shoulder measurement (plus ease). If your measurement is larger, widen the shoulders (see below). If it’s smaller, narrow the shoulders (see below). If it’s just right, or close enough to make you happy, then move on to your next challenge!

When you’re using a half front or back pattern piece (as most patterns come by default), you’ll measure from the center back (or center front) line (you may have to draw in an extended line if there’s a low neck or back) to the shoulder point. Make sure your ruler stays perpendicular to the center line. You’ll compare this measurement to half your full shoulder measurement (with ease). So if your shoulders measure 14.5, and you want one inch of ease, you’ll take 15.5/2, or 7.75 inches. If your measurements don’t match the pattern measurements, read on for adjusting!

Shoulder width adjustments

There are two main methods, which can be done in about a dozen ways, and have slightly different results.

The first changes the shape of the armscye, and the second changes the position of the underarm seam. Which one you’ll want to do depends on how happy you are with the underarm seam position.

It really depends on the pattern, but I find I’m most often happier with the second method, so that’s what I default to. This might be because I tend to do a pretty large wide shoulder adjustment (1/2–1 inch per shoulder). My narrow-shouldered friends seem to prefer the first method, but take a close look at where it’s adding and removing volume and decide for yourself.

Before you start

There are many ways to accomplish these alterations, but the result is the same. Here I’m showing where I physically slice up the pattern, because that’s the easiest to see. When I’m doing alterations for myself, however, I just trace it all out when I’m tracing the pattern. The result is the same though.

In all cases, you need to mark your seamlines (if the pattern includes seam allowance) before you begin. You can see images for how this looks below the two tutorials. Because of the shoulder slope, this is particularly important to get right. You should also consider reading through my post on the five questions to set yourself up for pattern altering success.

Method 1: change the armhole shape

Step 1: Cut the pattern

You can do this alteration by tracing, pivoting, cutting, or any combination. Because it’s easiest to see in the pictures (and when you’re doing it yourself), I’m physically cutting the pattern for this tutorial. Make sure you cut right at the shoulder point, and then pick a location about halfway through the armhole curve. The shape inside doesn’t matter, but I use a triangle just because it’s easy.

Step 2: Mark the new shoulder point

If you are widening the shoulder, you’ll need to attach some extra paper (I used purple so you can see it easily), extend the shoulder seam, and mark the new shoulder point.

If you’re are narrowing the shoulder, simply mark the new shoulder point location.

Step 3: Align the triangle

Align the top of the triangle with the new shoulder point and the bottom of the triangle right where you cut it on the armhole curve, and tape it in place. You may have to smooth out the curve, but for small adjustments it’s usually fine how it is.

Tips: Make sure you don’t accidentally flip the little triangle over or cover up any pattern markings!

Step 4: Cut off excess paper

Now just cut off the extra paper, and look with pride on your altered pattern! You’ll have to add or subtract exactly the same amount to both the front and back pattern pieces.

Method 2: change the underarm seam

Step 1: Cut the pattern

Because it’s easiest to see in the pictures (and when you’re doing it yourself), I’m physically cutting the pattern for this tutorial. Make sure you cut right at the shoulder point, and at the underarm point. This preserves the shape of the armhole. The shape inside doesn’t matter, but I’m using a rectangle this time.

Step 2: Mark the new shoulder point

First, attach extra paper—you’ll need it for both wide and narrow shoulder adjustments using this method.

If you are widening the shoulder, extend the shoulder seam, and mark the new shoulder point.

If you’re narrowing the shoulder, extend the underarm seam by drawing a straight line up from the current seam line (make it longer than you need; we’ll cut off the extra). Then, mark the new shoulder point location.

Step 3: Align the armhole curve

If you’re widening the shoulders, align the top of the armhole curve with the new shoulder point and the bottom of the armhole curve right wherever it hits along the side seam. You’ll have a triangle of extra paper sticking up that we’ll cut off.

If you’re narrowing the shoulders, align the top of the armhole curve with the new shoulder point, and the bottom of the armhole curve wherever it hits along the extended side seam.

Tip: Make sure you don’t accidentally flip the armhole curve over!

Step 4: Cut off excess paper

Now just cut off the extra paper, and look with pride on your altered pattern! You’ll have to add or subtract exactly the same amount to both the front and back pattern pieces.

Read this if your pattern includes seam allowance

If your pattern includes seam allowance, you’ll need to take an extra step or two. This will apply to patterns from Simplicity, McCall’s, Butterick, Vogue, as well as many independent pattern designers.

Patterns from Burda Style and some independent pattern designers do not include seam allowance, so you can do your alterations according to the instructions above, then add seam allowance before cutting.

Step 1: Mark your seam allowance

Draw in the stitching line along any parts of your pattern that need altering. Check your pattern instructions for how much seam allowance is included—this changes by company, and sometimes even for different parts of the pattern.

Step 2: Align stitching lines, not edges

Once you have your stitching lines marked, use them to make your alterations, NOT the edges of the pattern. This will give you some wonky looking corners, but once you trim them off neatly, it’ll work out just fine!

Comparing the two methods

Both methods add and subtract volume in slightly different places, so which one is best will depend on your pattern, your body, and your preferences. I usually prefer the second method, but I know the first is very popular also. Decide where you might like (or not mind) extra volume and choose accordingly.

Method 1 (altering the armhole curve) basically adds volume nowhere but the shoulder, but does change the shape of the armhole. Method 2 changes the side seam instead, adding a bit of volume through the upper chest.

Final thoughts

Shoulder adjustments are usually the first alterations you should make, since they change the fit of everything below (which is almost the rest of the garment). Width is the most common adjustment, but also consider shoulder slope and rounded shoulders.

What do you think? Let me know how your shoulder width adjustments are going, and feel free to ask questions either in the comments or by sending me a message!