A 38D bra fits a 38-inch ribcage with a D cup, typically matching a full bust of 42–43 inches and an underbust of 37–39 inches.
If you’re shopping for a 38D bra, the measurement question usually comes down to one thing: does the label match your body? The number 38 refers to the band size, measured snugly around your ribcage just under the bust. The letter D describes cup volume, which in US sizing generally represents about a 4-inch difference between the band and the fullest part of the bust. That puts a typical 38D at a 42–43 inch full bust, though every brand’s fit chart varies slightly.
What Do The Numbers 38 And D Mean Separately?
The 38 is the band size in inches — the measurement around your ribcage, taken snugly under the bust. The D is the cup letter. In US sizing charts, cup volume grows roughly one inch of bust difference per letter, so a D cup usually means the bust measures about 4 inches more than the band.
Two different body shapes can wear the same 38D label. One person might have a 37-inch underbust with a 42-inch bust; another might measure 39 inches under with a 43-inch bust. Both fit the general 38D range because bra fitting tolerates about a 2-inch spread on either dimension.
Skims’ size guide and Fruit of the Loom’s chart both place 38D in similar ranges, but they don’t match perfectly — more on that below.
How To Measure Yourself For A 38D Bra
Grab a soft measuring tape and follow these two steps. Do it in front of a mirror so you can confirm the tape stays level across your back.
- Measure the band: Wrap the tape snugly around your ribcage, right under your bust. The tape should sit flat and level, with the number landing between 37 and 39 inches to fit a 38 band. Round to the nearest even number.
- Measure the bust: Wrap the tape around the fullest part of your bust, keeping it loose enough that it doesn’t compress anything. A reading of 42 to 43 inches corresponds to a D cup on a 38 band.
When both numbers land in those ranges, a 38D bra will fit correctly. If your band measurement is close but your bust reads higher, you may be a 38DD; if it reads lower, a 38C could sit better.
What Sizes Are Equivalent To 38D In Other Countries?
| Size System | Equivalent 38D Conversion |
|---|---|
| US/Canada | 38D |
| UK | 38D |
| EU | 85D |
| Australia/NZ | 16D |
| France/Spain | 95D |
| Japan | 95D |
Nike’s size fit guide for women’s bras lists 38D in its US chart, and global conversions map it to 85D in Europe and 16D in Australia and New Zealand. The band measurement stays roughly constant across systems — only the numbering scheme changes. A 38D in US sizing is the same physical fit as an 85D in EU sizing, though minor variations exist between brands.
Why Doesn’t A 38D Fit The Same In Every Brand?
Bra sizing is not standardized. Skims, Fruit of the Loom, and Nike each publish their own fit charts, and the full bust measurement for 38D can vary by about an inch between them. This happens because brands cut their patterns differently — some run generous in the band, others in the cup.
The practical workaround is sister sizing. A 38D has the same cup volume as a 36DD and a 40C, so if a specific brand’s 38D feels tight in the band, try the 40C instead. If the cups feel small, the 36DD might work better.
When you find a brand that fits, stick with it. Your measurements haven’t changed — the brand’s interpretation of the numbers has.
If you’re ready to buy but want a trusted starting point, our tested roundup of the best bras for a 38D fit covers options that run true to size.
References & Sources
- Skims. “Bra Size Guide.” Lists US 38D with a band of 37–39 inches and a bust of 42–43 inches.
- Fruit of the Loom. “Women’s Bra Size Chart.” Maps US 38D to EU 85D and AU/NZ 16D with a 105 cm bust and 83 cm underbust.
- Nike. “Women’s Bra Size Fit Guide.” Lists 38D in its US size chart with conversion ranges for other regions.