BOSS Clothing Sizing

BOSS Clothing Sizing Guide: Regular vs Slim vs Relaxed | OD's Designer Clothing
BOSS engraved metal button on charcoal herringbone wool — Savile Row tailoring heritage

BOSS Clothing Sizing Guide

Regular vs Slim vs Relaxed | Chest, Waist & Inside Leg | XS–3XL Charts

By OD's Designer Clothing | Updated April 2026 | 6 min read

BOSS clothing comes in three distinct fits — Regular, Slim, and Relaxed — and the fit label matters more than the size label. A BOSS Slim Medium fits substantially differently to a BOSS Regular Medium. Understanding which fit you are buying is the most important step before checking the size chart.

This guide covers how to measure yourself, how each fit line compares, and what to expect from BOSS polos, knitwear, and outerwear specifically — where sizing conventions can differ from casualwear and t-shirts.

1 | The Three BOSS Fit Lines

BOSS labels its clothing with a fit descriptor on the product page, swing tag, and care label. The three current fit lines are:

Regular Fit

Classic, straight-cut silhouette. Room through the chest, waist, and hip. The most traditional BOSS cut — recommended if you prefer ease of movement or have a broader build. Sits off the body rather than against it.

Slim Fit

Modern, tapered cut. Closer to the body through the chest and shoulders, tapering at the waist. The most common cut in BOSS casualwear and polos. If you are used to high-street Regular fit, go up a size in BOSS Slim.

Relaxed Fit

Oversized, contemporary silhouette. Intentionally voluminous through the body and often with dropped shoulders. Reflects current streetwear trends. If in doubt, stick to your normal size — do not size down in Relaxed.

Critical Rule: Check the Fit Label First

  • A BOSS Slim Large fits similarly to a Regular Medium
  • A BOSS Relaxed Medium has more volume than a Regular Large in some garments
  • The fit label overrides all size assumptions — always identify it before consulting the chart

2 | How to Measure Yourself

Take measurements with a fabric tape measure. If you do not have one, use a piece of string and measure it against a ruler. Stand straight and relaxed — do not pull the tape tight.

Three Key Measurements

  • Chest: Measure around the fullest part of your chest, under the arms, keeping the tape horizontal. Do not inhale deeply when measuring.
  • Waist: Measure around your natural waist — approximately 2–3cm above the navel, at the narrowest point of your torso.
  • Inside leg: Measure from the crotch seam to the desired trouser break at the ankle. Stand against a wall with feet slightly apart. Have someone else measure for accuracy.

For tops: your chest measurement is the primary reference. For trousers: inside leg length and waist are both required — BOSS trousers are sized in waist inches with separate leg length options (30, 32, 34).

3 | BOSS Size Chart

All measurements in centimetres. These are body measurements — the garment will be cut larger to allow for fit and movement. "Chest to fit" means the measurement of your chest, not the garment itself.

Men's Tops — Regular Fit

Size Chest to Fit (cm) Waist to Fit (cm) Height Guide (cm)
XS 82–87 72–77 170–175
S 88–93 78–83 173–178
M 94–99 84–89 176–181
L 100–105 90–95 179–184
XL 106–111 96–101 182–187
2XL 112–117 102–107 184–189
3XL 118–123 108–113 185–190

Men's Tops — Slim Fit

BOSS Slim fit is cut approximately 4–6cm narrower in the chest than Regular fit at the same labelled size. Use this adjusted reference:

Size Chest to Fit (cm) Waist to Fit (cm) Recommended for Regular
XS 80–84 70–74
S 85–89 75–79 XS Regular
M 90–94 80–84 S Regular
L 95–99 85–89 M Regular
XL 100–104 90–94 L Regular
2XL 105–109 95–99 XL Regular
3XL 110–115 100–105 2XL Regular

Men's Trousers — Waist & Leg

Waist (inches) Waist (cm) Available Leg Lengths
28" 71cm 30 / 32 / 34
30" 76cm 30 / 32 / 34
32" 81cm 30 / 32 / 34
34" 86cm 30 / 32 / 34
36" 91cm 30 / 32 / 34
38" 96cm 30 / 32 / 34
40" 102cm 30 / 32 / 34

4 | Polos, Knitwear & Outerwear

Polo Shirts

BOSS polos are predominantly Slim fit. They are cut close to the body and sit neatly tucked or untucked. If you are broad across the shoulders, go one size up. The collar is firm and holds its shape well.

Knitwear (Jumpers & Cardigans)

BOSS knitwear varies. Merino and cotton crew necks are usually Regular or Slim fit. Chunky knits and cable knits tend to have more volume built in. Always check the fit label — knitwear does not stretch to accommodate sizing errors.

Outerwear (Coats & Jackets)

BOSS outerwear is cut to allow a mid-layer underneath. If you wear a Medium in t-shirts and jumpers, a Medium jacket will accommodate a hoodie or light knitwear underneath. For heavy knitwear or a thick jumper, go up a size in the jacket.

T-Shirts

BOSS t-shirts are predominantly Slim fit and designed to sit close. They can feel snug across the chest compared to high-street equivalents. Customers who prefer a relaxed t-shirt feel should go up one size or look for Relaxed-labelled styles.

5 | Italian Sizing on Selected Pieces

Some BOSS tailoring, premium knitwear, and occasion pieces use Italian sizing — labelled in even numbers (46, 48, 50, 52, 54, 56, 58) rather than letter sizes (S, M, L).

Italian to UK Letter Size Conversion

  • Italian 44 = XS
  • Italian 46 = S
  • Italian 48 = M
  • Italian 50 = L
  • Italian 52 = XL
  • Italian 54 = 2XL
  • Italian 56 = 3XL

Italian sizing typically corresponds to the chest measurement in centimetres, divided by 2. An Italian 50 = approximately 100cm chest, which aligns with a Large. This is not a universal rule but it provides a useful cross-check when a garment has both Italian and letter sizing labels.

Check the Label Format

If a BOSS garment is labelled with a number (e.g. 50), it uses Italian sizing. If labelled with a letter (e.g. L), it uses the standard letter system. The size charts in this guide apply to the letter system.


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