The same garment can be labelled 42, L or 52 depending on the country and the cut. For jackets and blazers the chest or bust decides the size, and height decides the length. This calculator takes your chest or bust and height and gives the letter size, the number size and the European equivalent, from Nike’s tops charts and the usual men’s jacket convention.
How to use the jacket and blazer size calculator
- Choose men’s or women’s sizing.
- Measure the chest or bust at the fullest part, under the arms, tape level.
- Enter your height.
- Read the result: letter size, number size, EU size and length.
Jacket size formula
letter = Nike chart band containing your chest (or bust)
length from height: Short, Regular, Long, Extra Long (men); Tall from 5′8″ (Nike women)
The letter ranges are Nike’s tops charts (retrieved 2026-10-15), which are body measurements. The men’s number follows the measuring method in the MensUSA suit-size guide and the EU conversion on Wikipedia. The tables list both.
Men
| Men’s size | Chest (in) | Chest (cm) | Even-inch jacket sizes it covers |
|---|---|---|---|
| XXS | 28.1 – 31.5 | 71 – 80 | 30 |
| XS | 31.5 – 35 | 80 – 89 | 32, 34 |
| S | 35 – 37.5 | 89 – 95 | 36 |
| M | 37.5 – 41 | 95 – 104 | 38, 40 |
| L | 41 – 44 | 104 – 112 | 42, 44 |
| XL | 44 – 48.5 | 112 – 123 | 46, 48 |
| XXL | 48.5 – 53.5 | 123 – 136 | 50, 52 |
| 3XL | 53.5 – 58 | 136 – 147 | 54, 56, 58 |
| 4XL | 58 – 63 | 147 – 160 | 60, 62 |
Women
| Women’s size | Bust (in) | US | UK | EU |
|---|---|---|---|---|
| XXS | 27.5 – 29.5 | 0 | 2 | 30 |
| XS | 29.5 – 32.5 | 0–2 | 4–6 | 32–34 |
| S | 32.5 – 35.5 | 4–6 | 8–10 | 36–38 |
| M | 35.5 – 38 | 8–10 | 12–14 | 40–42 |
| L | 38 – 41 | 12–14 | 16–18 | 44–46 |
| XL | 41 – 44.5 | 16–18 | 20–22 | 48–50 |
| XXL | 44.5 – 48.5 | 20–22 | 24–26 | 52–54 |
Worked example
A man has a 42 inch chest and is 5′10″ tall.
- Letter: 42 is within 41–44 → L.
- Number: 42, EU 52, length Regular, so a 42R.
Buying tips
- Shoulders: the shoulder seam should end at the edge of your shoulder; this cannot be altered easily.
- Layers: try the jacket over the layer you will wear most.
- Sleeves: they can usually be shortened by a tailor, so lean to the longer length if between.
- Brand cuts differ: slim, regular and relaxed fits can change the size you need by one.
For a full suit see the Suit Size Calculator, and to convert to other countries the Clothing Size Converter (International). This page offers general guidance.
Sources
Every figure above comes from these pages, read directly on the dates shown. Brand names are used only to identify published charts.
- Nike — men’s tops size chart — checked 2026-10-15
- Nike — women’s tops size chart (international conversions, tall tops) — checked 2026-10-15
- MensUSA — suit and jacket size chart (height bands) — checked 2026-10-15
- Wikipedia — Clothing sizes (men’s suit EU conversion) — checked 2026-10-15
Frequently asked questions
How do I find my jacket size?
Measure the fullest part of your chest (men) or bust (women) under the arms with the tape horizontal. For men, a tailored jacket size is that number rounded to the nearest even inch; casual jackets use letters. Women’s jackets follow the bust ranges on Nike’s tops chart.
What is the difference between a jacket and a blazer size?
The chest measurement is the same. A blazer is tailored and labelled in numbers (38, 40, 42) with a length letter, while many casual jackets and bomber styles use letters (S, M, L). The calculator gives both.
How does height change the size?
Height decides the length, not the chest size. MensUSA bands: Short 5′4″–5′7″, Regular 5′7½″–5′11″, Long 5′11½″–6′2½″, Extra Long 6′3″+. Nike’s tall tops, for 5′8″ to 6′, are 1.75 in (4.5 cm) longer.
Should I size up for layering?
If you will wear thick knitwear under a jacket, many people go up a size, but a tailored blazer should fit the shoulders closely. See the Suit Size Calculator for tailored fit.
What about the EU number?
For men, EU = UK/US jacket size + 10 (Wikipedia). For women, the EU sizes come from Nike’s conversion table: a medium is EU 40–42.