How to Choose the Right Size When Buying a Leather Jacket
Leather jackets don't forgive sizing errors the way fabric garments do. The shoulder can't be altered. The leather won't stretch to compensate. Getting the size right before you buy is the single most important thing you can do — and it takes less than five minutes.
Unlike a cotton shirt or a knit jumper, a leather jacket has very specific fit requirements that can't easily be fixed after the fact. A shoulder seam in the wrong position is essentially permanent. A chest that's too tight won't loosen meaningfully over time. This guide walks you through exactly how to measure yourself, how to read Decrum's size charts for both men and women, and how to make the right call when you're between sizes.
Step 1 — Measure Yourself Correctly
Before comparing anything to a size chart, you need two accurate measurements: your chest or bust circumference and your shoulder width. Everything else is secondary. Here's exactly how to take them:
Chest / Bust Measurement
Wrap a soft measuring tape around the fullest part of your chest — across the shoulder blades at the back, under the armpits, and across the widest point of the chest or bust at the front. Keep the tape parallel to the floor. Arms relaxed at your sides. One finger of clearance between tape and body — snug but not tight. This is your body chest measurement in inches.
Shoulder Width (Critical for Leather)
Measure across the back from shoulder tip to shoulder tip — from one acromion (the bony point at the very edge of each shoulder) to the other. This is your across-shoulder measurement. In leather, this is the number that matters most: the shoulder seam cannot be moved after a jacket is made. If you can only get one measurement right, make it this one.
Measuring Alone — the Wall Method
For solo shoulder measurement: stand with your back lightly against a wall, mark your two shoulder tips on the wall with a light pencil mark, then step away and measure between the marks. Far more accurate than trying to reach around yourself with a tape. For chest measurement alone, a full-length mirror helps confirm the tape is level at the back.
Measure Twice, Use the Larger Reading
Take each measurement twice. If the two readings differ, use the larger one — particularly for shoulder width. A jacket sized to the slightly narrower reading will feel restrictive; one sized to the slightly wider reading will fit correctly. In leather, tight is always the wrong error.
Step 2 — Find Your Size in the Charts
Decrum jackets run true to size. Compare your body chest measurement directly to the chart below — no need to add ease, the fit allowance is already built into each size. Both charts show body measurements in inches.
Men's Size Chart
Body Measurements (Chest)
| SIZE | CHEST (IN) |
|---|---|
| XS | 37 – 38 |
| S | 39 – 40 |
| M | 41 – 42 |
| L | 43 – 44 |
| XL | 45 – 46 |
| XXL | 47 – 48 |
| 3XL | 49 – 50 |
Women's Size Chart
Body Measurements (Bust)
| SIZE | US | BUST (IN) |
|---|---|---|
| XS | 4 | 33 – 34 |
| S | 6 | 35 – 36 |
| M | 8 | 37 – 38 |
| L | 10 | 39 – 40 |
| XL | 12 | 41 – 43 |
| XXL | 14 | 44 – 46 |
| 3XL | 16 | 47 – 49 |
Find your chest or bust measurement in inches and match it to a size. If your measurement falls exactly on a boundary (e.g., Men's 40 inch could be S or M), choose the larger size. Leather does not stretch to accommodate a too-tight fit — but a slightly larger size can always be worn over a lighter layer.
Step 3 — What to Do When You're Between Sizes
Being between sizes is the most common sizing situation and the one that causes the most uncertainty. The rule for leather is different from other materials: always go up, not down. Here's why — and how to make the larger size work.
Leather has very limited stretch capacity compared to fabric. A jacket that is too tight in the chest will remain too tight regardless of how much you wear it — the collagen fibre structure simply doesn't expand enough to make a meaningful difference. A jacket that is one size up from your body measurement will have a small amount of additional chest volume that can be filled naturally with a thin layer underneath — a fitted tee or a light knit.
The exception is shoulder width. If sizing up would put the shoulder seam noticeably beyond your shoulder tip — hanging down the upper arm rather than sitting at the shoulder bone — the larger size is not the answer. In that case, size down and accept that the chest may be very close-fitting, which for a slim profile can actually look intentional.
The shoulder seam position is the one measurement that cannot be corrected after purchase. Every other dimension can be accommodated — the shoulder cannot.
Step 4 — Fit Tips Before You Order
Measure Over a Fitted Tee
Take your chest measurement while wearing the base layer you'll typically wear under the jacket — not over a thick jumper, not bare-chested. This gives you a realistic fitting measurement.
Shoulder Seam = Non-Negotiable
In leather, the shoulder seam cannot be moved by a tailor without essentially rebuilding the jacket. If the seam falls off your shoulder tip, the jacket will never look right. Prioritise this above all other measurements.
Leather Runs True to Size
Decrum jackets run true to size — no need to size up speculatively. Simply find your chest or bust measurement in the chart and that is your size. Only consider sizing up if you plan to layer heavily underneath.
Test Range of Motion
A correct leather jacket fit allows you to cross your arms, reach forward, and sit down without pulling or significant restriction. If you receive your jacket and any of these feel restricted, it may be too small.
Inches, Not Centimetres
Decrum's size charts use inches. If your tape measure shows centimetres, divide by 2.54 to convert — or use the conversion: 1 inch = 2.54 cm. Most online converters work well for this.
Free Returns — Order with Confidence
If you receive your jacket and the fit isn't right, Decrum offers 30-day easy returns. Measure carefully, order confidently, and exchange if needed — with no hassle.
Layering — How It Affects Your Size Choice
One of the most common reasons people size up in a leather jacket is to accommodate a layer underneath — a hoodie, a thick knit, or a mid-layer for colder months. If this is your intention, going one size up from your body measurement is the right call. The additional chest volume in the next size will accommodate a standard-weight knit or light hoodie comfortably without the jacket pulling across the back.
For very heavy layers — heavyweight hoodies, thick wool knits — going up two sizes may be needed. In this case, pay special attention to the shoulder seam when the jacket arrives: two sizes up may create a noticeable shoulder seam drop. Try the jacket with the intended layer first and assess the shoulder position before deciding whether the fit is working.
For a clean, fitted silhouette without layers — the look in most Decrum product photos — your body measurement size is correct. The jackets have sufficient ease built in for comfortable movement over a fitted tee or shirt without any additional volume.
Before ordering: measure your chest or bust (in inches) → find your size in the chart → confirm the shoulder width measurement is consistent with that size → decide whether you want a fitted or layering silhouette → order. The entire process takes five minutes and eliminates the most common sizing errors.
Frequently Asked Questions
