How To · Fashion · Build
Find Your Correct Shirt Size in Three Measurements
A well-fitting shirt starts with knowing your numbers. We'll walk you through the three measurements that matter—and why off-the-rack sizing fails most men.
5 min read · IrisMost men buy shirts by guessing. They grab a medium or large, try it on, and hope. The result: collars that gape, sleeves that bunch, or chest panels that pull. The fix is simpler than you think—three measurements, taken correctly, will eliminate the guesswork forever.
Shirt sizing is not standardized across brands, which means your size at one retailer may not match another. But your actual body measurements do. Once you know them, you can shop with confidence and spot a good fit in seconds.
Your neck measurement is the anchor. Everything else—chest, sleeve length, and overall cut—hangs from that single number.
Step one · 2 minutes
Measure your neck
Wrap a soft tape measure around the base of your neck, where a collar sits. Keep the tape snug but not tight—you should be able to slip one finger underneath. Write down the measurement to the nearest half-inch. This is your collar size. Most men fall between 14 and 17 inches; this number rarely changes unless you gain or lose significant weight.
Measure in the morning before your neck swells from activity. Avoid measuring over a shirt collar or thick fabric.
Step two · 2 minutes
Measure your chest
Wrap the tape measure around the fullest part of your chest, usually at nipple level. Keep your arms relaxed at your sides. The tape should be parallel to the ground and snug without compressing your ribcage. This measurement determines how much room you have across the front and back. Add one to two inches to this number—that's your shirt size in inches.
Measure over a thin t-shirt if you prefer, but be consistent. A 38-inch chest typically wears a size 38 or 39 shirt, depending on desired fit.
Step three · 2 minutes
Measure your sleeve length
Extend your arm at a 90-degree angle, keeping your hand relaxed. Have someone measure from the center of your back neck, across your shoulder, down to your wrist bone. This is your sleeve length. Alternatively, measure from your shoulder seam to your wrist while wearing a well-fitting shirt. Most men range from 31 to 36 inches; this can vary based on proportions.
Sleeve length is often overlooked but critical. A shirt with sleeves too short will ride up when you bend your arms; too long and you'll drown in fabric.
Step four · 1 minute
Write down your numbers
Record your three measurements clearly: collar size (e.g., 15.5), chest size (e.g., 39), and sleeve length (e.g., 33). Take a photo of this note and save it in your phone. This becomes your reference sheet for every shirt purchase, whether online or in-store. You now have the foundation to evaluate fit across any brand.
Brands vary in how generously they cut. A 39-inch chest at one retailer may fit differently than at another. Use these numbers as a starting point, then try on to confirm.
Step five · 2 minutes
Understand fit preferences
Shirt fit comes in three categories: slim (minimal ease, closer to your body), regular (standard room through the chest and torso), and relaxed (generous room, looser silhouette). Your measurements tell you size; fit preference tells you cut. A 39-inch chest might wear a slim-fit 38 or a regular-fit 39, depending on whether you prefer a tapered or roomy feel. Try both to discover your preference.
Slim-fit shirts suit athletic builds; regular fits work for most; relaxed fits hide a softer midsection. Neither is better—it's about what makes you feel confident.
Step six · 1 minute
Verify fit when you try on
When trying on a new shirt, check three points: the collar should sit flat against your neck with no gap; the shoulder seam should land at the edge of your shoulder, not down your arm; and the hem should hit mid-fly on your pants. Sleeves should end at your wrist bone. If any of these fail, the shirt doesn't fit, regardless of the size label. Trust your eyes and body, not the number.
Fit is more important than size. A shirt that fits perfectly at a different size is better than a misfit in your 'correct' size.
How to know it works.
You've nailed your size when you can button the shirt comfortably, move your arms freely, and see no pulling across the chest or back. The collar should feel secure without choking, and sleeves should end exactly at your wrist. You should feel confident, not constrained.
Questions at the mirror.
I'm between sizes. Should I size up or down?
Size up. A slightly loose shirt is easier to tailor or live with than one that's too tight. Tight shirts restrict movement and wear out faster at stress points like the buttons and seams.
My neck and chest measurements suggest different sizes. What do I do?
Prioritize your neck measurement—it's the hardest to alter. If your neck is 15.5 and chest is 40, buy a 40-inch shirt with a 15.5 collar. The body can be tailored; the collar cannot.
Do I need to remeasure if I gain or lose weight?
Yes. Weight changes affect chest, sleeve length, and sometimes neck. Remeasure every 10–15 pounds of change to stay accurate.
Why do my sleeves always feel too short?
You may have longer proportions relative to your height. Measure from your shoulder seam to wrist while wearing a well-fitting shirt, not from your neck. Some brands also cut sleeves shorter than standard.
Can I use my old shirts to figure out my size?
Only if they fit well. Lay a well-fitting shirt flat and measure the collar, chest (armpit to armpit, doubled), and sleeve length. Compare to your body measurements to spot inconsistencies in that brand's sizing.