XXXXL Size 18: What Size Is 4XL in Numbers?
Sometimes. Calvin Klein's plus size women's 4XL covers US 16–18, but Nike's women's 4X is a US 30W–32W, so the answer depends on the brand and size line.
Where is this 4XL from?
58–63 in chest147–160 cm chest
Nike men's 4XL, body measurement
Is it a size 18? Nike's men's tops chart has no numeric size for this.
Source: Nike men’s chart, checked November 2026.
XXXXL and Size 18: What the Numbers Actually Mean
"Size 18" can mean three different things, so start with the one that matches what you are buying.
Women's size 18
This is the most common meaning. On the charts we checked, a US 18 falls at XL in Nike's regular line, 1X in Nike's plus line, and 4XL in Calvin Klein's plus size line. The same number gets three different labels.
Kids' or youth size 18
Target's girls chart labels a size XXL (18), for a 36 inch chest. That is a child's size and is far smaller than an adult 4XL.
Men's sizes
Nike's men's tops chart uses letters with chest measurements and has no size 18. If a men's shirt is labeled 18, check whether the number refers to the neck.
Why brands differ
Each brand publishes its own chart, so a label only has meaning next to that brand's numbers. Marketplace listings can differ even more: one Amazon seller labels an "Asian 4XL" as a US X-Large.
Size 18 on four official charts
| Chart | Label | Listed as |
|---|---|---|
| Calvin Klein plus size tops | 4XL | US 16–18 |
| Nike women’s regular | XL | US 16–18 |
| Nike women’s plus | 1X | US 18W–20W |
| Target girls | XXL (18) | Child’s size 18 |
Checked November 2026. Always go by the official chart for the item you are buying.
18 and 18W are not the same size
Nike's regular women's chart puts US 16–18 at XL, and its plus chart puts US 18W–20W at 1X. The XL lists a 41–44.5 inch bust and the 1X lists 47–49.5 inches. That is 5 to 6 inches apart for two sizes that both contain the number 18. The W after the number tells you which line you are reading, so look for it in the listing.
| Label | Chest or bust | Waist | Hips |
|---|---|---|---|
| Nike women's XL | 41–44.5104–113 | 34.5–38.588–98 | 44–47112–119 |
| Nike women's 1X | 47–49.5119–126 | 43–45.5109–116 | 51–54130–137 |
| Nike women's 4X | 55–58140–147 | 53–57135–145 | 61–65155–165 |
| Target girls' XXL (18) | 3691 | 30.577 | 3794 |
Nike's women's 4X sits well above both, at a 55–58 inch bust, and Nike lists it as US 30W–32W. Target's girls size is at the other end, with a 36 inch chest, a 30.5 inch waist and 37 inch hips.
How to tell which size 18 a listing means
- Check the department. Women's, girls' and men's listings use the number differently.
- Look for a W. At brands that sell both lines, 18W points to the plus line and 18 to the regular line.
- Find the letter beside the number. Target's girls chart writes XXL (18), which is a child's size even though XXL appears in the label.
- Open the chart for that item. Compare the measurements, and check whether they describe the garment laid flat or the measurement it is meant to fit.
Size 18 in US, UK and EU
A UK 18 is not a US 18. In Calvin Klein's plus size tops and dresses, the 4XL is US 16–18, UK 20–22 and EU 48–50, while the 3XL is US 14–16, UK 18–20 and EU 46–48. Other brands may publish different pairs, so use the size label converter as a starting point and confirm on the brand's own guide.
Before you order
Measure your bust, waist and hips, then compare them with the chart for that exact item. A label or a number alone is not enough.
Questions
Is size 18 an XXL?
It depends on the line. Nike's regular women's chart puts US 16–18 at XL and US 20–22 at XXL. In Target's girls chart, XXL is labeled size 18, and that is a child's size.
Is a 3XL a size 18?
Not at the brands we checked. Calvin Klein lists its plus size 3XL as US 14–16, and Nike lists its 3X as US 26W–28W.
Is 4XL XXL?
No. XXL is 2XL, so a 4XL is two label sizes larger.
Is size 18 the same as 18W?
Not at Nike. Its regular XL includes US 18 and lists a 41–44.5 inch bust. Its plus 1X includes 18W and lists a 47–49.5 inch bust.
What is a US 18 in UK sizes?
It depends on the brand. Calvin Klein's plus size tops and dresses list US 16–18 as UK 20–22 and EU 48–50.
Is XXXXL a kids size?
Not on the charts we checked. Target's girls XXL (18) lists a 36 inch chest, far below Nike's men's 4XL at 58–63 inches.