How to Measure Your Shoulder Width for Shirts and Jackets
Of all the numbers on a size chart, shoulder width is the one that decides whether a shirt or jacket can be worn at all. Here are three methods, two charts, and the rules every shopper should know.
You buy a dress shirt online. The chest fits. The sleeves are the right length. But the shoulder seam sits two inches down your arm, like the shirt is sliding off.
Or the opposite. The seam digs into the top of your shoulder. You can't lift your arms without the whole shirt riding up.
Both problems come from the same place. Wrong shoulder width.
Of all the measurements that matter for a shirt or jacket, this is the one. Get it right and the rest can be tailored. Get it wrong and the garment is unwearable, no matter how good the chest, waist, and length numbers are.
This guide covers what shoulder width actually is, why it matters more than every other measurement, and how to measure it accurately even when you are alone. Includes a chart for both men and women.
What Shoulder Width Is
Shoulder width is the straight-line distance across your back from the bony point of one shoulder to the bony point of the other.
The bony point is called the acromion. You can feel it. Run your finger from your neck along the top of your shoulder until you hit the bump where the bone ends and your arm begins. That bump is the landmark.
Shoulder width is measured between those two points, going across your back, not your front, and not curving over the muscle.
Don't trust seams on a shirt that doesn't fit
Why Shoulder Width Matters More Than Chest Size
Three reasons shoulder width is the most important number for shirts and jackets.
Reason 1: Shoulders cannot be tailored larger
Reason 2: The eye sees shoulders first
Reason 3: It dictates the entire fit
For dress shirts, suit jackets, blazers, sport coats, and even structured t-shirts, shoulder width is the foundation.
What You Need
- A soft fabric measuring tape.
- A friend, ideally.
- A wall and a mirror, if you are alone.
- A shirt or jacket that fits you well (optional, for the easier method).
A friend makes this measurement much easier because it is taken across your back, where you can't see. If you are alone, the easier path is to measure a garment you already own.
Method 1: From a Shirt or Jacket That Fits
This is the fastest method and works for almost everyone.
Pick a shirt that fits in the shoulders
The seam should sit right at the bony point of your shoulder — not on your arm and not on your neck.
Lay the garment flat
Place it on a bed or table. Smooth it out. Button it up if it has buttons.
Find the two shoulder seams
These are the seams where the sleeve attaches to the body of the shirt, at the highest point of each shoulder.
Place the tape at the outer edge of the left seam
Right at the outermost point where the seam meets the sleeve cap.
Run it across the back to the right seam
Keep the tape flat against the fabric. Do not let it curve over the yoke or sag.
Read and record
That is your shoulder width. Write it in both inches and centimeters.
Method 2: From Your Body, With a Friend
This is the most accurate method but you need a second person.
Stand straight, arms relaxed
Wear a thin t-shirt or no shirt at all. Bulky clothing throws the number off.
Find the bony tip on each shoulder
Have your friend press lightly to feel the acromion bump on each side — the point where the bone ends and your arm begins.
Place the tape at the bony point of one shoulder
Anchor it firmly so it doesn't slide while the other side is set.
Run the tape straight across your upper back
All the way to the bony point on the other shoulder. The tape should follow a flat path, not curve over the muscle of your upper back.
Read the number
The tape should sit just above your shoulder blades, not on top of them.
Method 3: From Your Body, Alone
If you don't have a friend or a shirt that fits, this method works. It takes a bit of setup.
Stand against a wall
Back flat to the wall. Arms relaxed at your sides.
Place a hardcover book against the wall
Pressed lightly against the bony point of one shoulder.
Mark the inner edge of the book on the wall
Use a piece of tape or a pencil at the edge closest to your neck.
Repeat on the other side
Book against the bony point of the other shoulder. Mark the inner edge.
Measure the distance between the two marks
That is your shoulder width.
Margin of error: about half an inch
Shoulder Width Chart — Men's
Match your shoulder width to the typical men's shirt or jacket size.
| Shoulder Width | Shoulder (cm) | Shirt Size | Jacket Size |
|---|---|---|---|
| 16" | 41 cm | XS | 36 |
| 17" | 43 cm | S | 38 |
| 18" | 46 cm | M | 40 |
| 19" | 48 cm | L | 42 |
| 20" | 51 cm | XL | 44 |
| 21" | 53 cm | XXL | 46 |
These are averages across global brands. Slim-fit and athletic-fit shirts may run 0.5 to 1 inch narrower in the shoulder than the chart shows.
Shoulder Width Chart — Women's
| Shoulder Width | Shoulder (cm) | Shirt Size | Jacket Size |
|---|---|---|---|
| 13" | 33 cm | XS | 0 / 2 |
| 14" | 36 cm | S | 4 / 6 |
| 15" | 38 cm | M | 8 / 10 |
| 16" | 41 cm | L | 12 / 14 |
| 17" | 43 cm | XL | 16 / 18 |
| 18" | 46 cm | XXL | 20 / 22 |
Women's blazers and structured tops vary more by brand than men's do. Always check the brand's specific size chart, especially for fitted or tailored cuts.
Five Mistakes That Wreck Your Shoulder Measurement
Measuring across the front
Shoulder width is taken across the back. The front gives you a different and shorter number.
Curving the tape over your muscles
A tape that follows the contour of your upper back reads longer than the real shoulder span. Keep it flat.
Measuring on a sloped shoulder
Hold your shoulders level. Slumping forward changes the number by half an inch or more.
Using a shirt that does not fit
If the shirt's shoulder seam sits on your arm, the seam-to-seam number is bigger than your real shoulder. Garbage in, garbage out.
Ignoring asymmetry
Most people have one shoulder slightly higher or wider than the other. Measure both halves separately if you can. Use the bigger half doubled.
Slim Fit, Regular Fit, Oversized: How Shoulder Width Changes
Different fits use the shoulder differently.
Slim and tailored fit
Regular fit
Relaxed and oversized fit
Drop-shoulder
For dress shirts and suit jackets, treat slim fit as the default for online shopping unless the brand specifically states otherwise. Slim fit is the cut most likely to fail at the shoulder if you guess your size.
When to Size Up vs. When to Size Down
If your shoulder number falls between two sizes, the rule depends on the garment.
- Dress shirts: size up. A shirt that pulls at the shoulder will tear at the seam. A slightly loose shoulder reads as relaxed, not sloppy.
- Suit jackets and blazers: size up, then have the chest and waist taken in. A tailor can slim the body. They cannot widen the shoulder.
- Casual button-downs and t-shirts: size down if you want a fitted look, up if you want relaxed.
Between sizes across every brand?
FAQs
Can I measure shoulder width over a shirt?
Yes if the shirt is thin and fits well. Avoid sweaters and jackets, which add bulk and inflate the number.
Is shoulder width the same as "across back"?
No. Across back is measured a few inches lower, between the armpits, not at the shoulder bones. The two numbers are usually within 1 inch but they are not the same.
My shoulders are uneven. Which one do I use?
Measure both halves separately and double the bigger number. That is your effective shoulder width — the garment has to clear the wider side.
Why does my shoulder size differ between brands?
Sizing is not standardized. American, European, and Asian brands all run differently. Even within one country, slim-fit and athletic-fit lines can vary by an inch.
Do I need to measure shoulder for t-shirts?
For fitted or athletic t-shirts, yes. For relaxed or oversized t-shirts, no — the shoulder seam sits on the bicep by design and shoulder width does not drive the fit.
Can a tailor widen a too-narrow shoulder?
No. Shoulders cannot be tailored larger. The shoulder seam, sleeve cap, and lining are all locked in. If the shoulder doesn't fit, the garment is done.
Save It Once, Use It Forever
Shoulder width does not change for adults. Measure it once, write it down, never measure it again.
Add it to your size note:
- Bust or chest
- Waist
- Hips
- Inseam
- Outseam
- Shoulder width
- Sleeve length
Seven numbers. That is the full set for any shirt, jacket, dress, or pant on any website. Measure once. Reuse forever. Stop returning clothes that were never going to fit. Stores running Tailor Size Guide let shoppers save these numbers and reuse them across every product in the store.
Selling shirts, jackets, or suits on Shopify?
The biggest hidden cost in your store is shoulder-width returns. Tailor Size Guide lets shoppers enter their measurements once and matches them to the right size on every product page — before they buy.