From a 16.5-inch (42 cm) neck, ready-to-wear gets tight. You go up a size to avoid choking, and the shirt balloons at the chest. You stay at your "normal" size, and the collar squeezes you.
Our solution is different: your exact neck size, to the centimetre, calculated by our AI — without changing the rest of the shirt.
Two topics, often confused — including by search engines.
A spread collar is a style of collar — Italian, cutaway — whose points sit further apart than usual. It's a style choice, independent of your morphology. If that's what you're after, see our long collar shirt instead.
A thick neck, on the other hand, is a feature of your morphology: the measurement of your neck. This page only covers that subject.
The average adult man's neck measures between 14 and 17 inches (36 to 43 cm). Above 16.5 inches (42 cm), classic ready-to-wear starts to fall short — that's where mainstream brands cap out or impose compromises.
A few concrete benchmarks:
| Neck size | Standard shirt size |
|---|---|
| 15 in (38 cm) | S |
| 15.5–16 in (39–40 cm) | M |
| 16–16.5 in (41–42 cm) | L |
| 17–17.5 in (43–44 cm) | XL |
| 18–18.5 in (45–46 cm) | XXL |
| 18.5+ in (47 cm+) | XXXL and above |
Beyond 17.5 inches (44 cm), supply shrinks dramatically. Beyond 18 inches (46 cm), it almost disappears, except in plus sizes — with all the compromises that come with them.
Our offer covers every neck size from 14 to 23.5 inches (35 to 60 cm), to the exact cm, at no extra cost.
The natural reflex when the collar squeezes is to go up a size. But a ready-to-wear shirt is sized as a single block: if you go up a size for the collar, the chest, the waist, the shoulders and the sleeves go up too. Result: the collar fits, but everything else floats.
That's the parachute effect: fabric ballooning at the chest, armholes that drop, sleeves too long. You gain ease where you didn't need it, and you lose the fit.
Brands specialised in plus sizes solve this by making everything wider — not by keeping a fitted chest with a wider neck. It's not the same need.
A custom shirt isn't a single block. It's made of a dozen independent measurements — neck, chest, hips, shoulder width, sleeve length, etc. Each is calculated for your morphology, with no domino effect.
Our AI-driven sizing is trained on more than 50,000 customers. You enter your weight, height, age, and answer 3 questions. It calculates your fit in seconds — including your neck, to within 0.2 inches (0.5 cm). No measuring tape. No fitting appointment.
If your neck is 17.1 inches (43.5 cm), your collar will be 17.1 inches (43.5 cm). Not 17, not 17.5 — 17.1. And the chest stays tailored to your chest, not to a standard XL.
This fit is then encoded in your Fit Key — a 5-character code, patented in 2012, printed inside the back yoke of every shirt. It compiles all the measurements of your shirt. For your next order, one click is enough.
Doesn't matter. Our AI doesn't need you to know it. It deduces it from your weight, height, age, and answers to the 3 questions. 81% of our customers get the correct fit on the first try.
If the first shirt is half an inch off your ideal — collar slightly too loose or too tight — you adjust the fit in one click. You automatically receive a new Fit Key for your future orders.
And worst case, our 100-day Fit Guarantee takes over: we remake the shirt, in most cases without a physical return. Our actual return rate is 5%, versus 20–30% in fashion e-commerce.
Neck size and collar shape are two different dimensions. At equal neck size, some shapes visually open up the neck, others tighten it.
For more, see our complete shirt collar guide.
Method 1 — with a measuring tape. Place the tape at the base of your neck, just below the Adam's apple. Slide one finger between the tape and your skin to keep ease. Read the measurement.
Method 2 — with a shirt that fits you well. Unbutton the collar fully. Lay it flat. Measure with a measuring tape from one buttonhole to the other.
Add half an inch (1 cm) for ease and any shrinkage in the wash. And in any case, our AI does the calculation for you — this measurement is optional.
To wrap up. A shirt that no longer squeezes at the collar, no longer floats at the chest, and reorders in one click. Custom shirts in European fabric from €99, B Corp certified, shipped without flying, 100-day Fit Guarantee.
Between 14 and 17 inches (36 to 43 cm) for an adult man, depending on morphology. Above 16.5 inches (42 cm), we generally talk about a thick neck.
From 16.5 inches (42 cm) in practice — that's the threshold where classic ready-to-wear starts to fall short or impose compromises.
Measuring tape at the base of the neck, below the Adam's apple, with one finger of ease. Or laid flat, from one buttonhole to the other, on a shirt that fits you. Add half an inch (1 cm) for ease.
In ready-to-wear, 16.5 inches (42 cm) is an L, 17–17.5 inches (43–44 cm) an XL, 18–18.5 inches (45–46 cm) an XXL. At LE CHEMISEUR®, your neck is made to the exact cm — not converted into a size.
That's the parachute effect. Ready-to-wear is sized as a single block: going up a size for the collar means going up a size at the chest, shoulders and sleeves too. Custom tailoring treats these measurements independently.
Our AI handles necks up to 23.5 inches (60 cm), at no extra cost.
Cutaway (Italian) or classic forward-point collar. Avoid the band collar, which tightens directly at the base of the neck. Our complete shirt collar guide.
You adjust the fit in one click and receive a new Fit Key for your future orders. The 100-day Fit Guarantee covers the rest, in most cases without a physical return. Guarantee details.
From €99 in European fabric. Our best-seller in French fabric is €129. No extra cost for a thick neck. See our shirts.
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