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Bra Fitting Guide

38A Bra Size Guide

38A bra size explained: measurements, sister sizes, international equivalents, and fit tips.

By Claire Bennett
2 min read • Updated Nov 2026
Direct Fit Answer

A 38A bra means a 38-inch band with an A cup, or roughly a 1-inch difference between underbust and bust measurement.

This size sits right in the range most mainstream retailers stock in-depth, so availability usually isn't the challenge. Fit precision is.

38A bra size chart showing 37" to 38" underbust, 39" bust, 590 cc cup volume, and sister sizes
Size 38A Chart
US 38A fits a 37" to 38" snug ribcage and 39" full bust (~590 cc per cup), matching UK 38A and EU 85A.Bra-SizeCalculator.com Guide
Size 38A Quick Reference

38A Measurements, Cup Volume & Global Sizes

Verify My Size
Snug Underbust Ribcage37" – 38"94–97 cm ribcage
Fullest Bust Perimeter~39"+1" over band (99 cm)
Single-Cup Volume~590 ccPair tissue ~2.5 lbs (1121 g)
Bralette & Lounge ScaleXLAlpha wireless equivalent
Snugger Band Sister36B
View 36B →
Target Size38A (~590 cc)
Baseline
Roomier Band Sister40AA
View 40AA →
38A Across 7 Global Lingerie Tag Standards
US38A
UK38A
EU85A
AU16A
FR100A
IT5A
JPA85
Size 38A Picks

Bras That Fit Well in Size 38A on Amazon

Picked for steady 38-band support and true A-cup depth, with no paid brand placements.

Search All 38A on Amazon
Champagne blush deep-plunge contour underwire bra with flat scalloped floral mesh-lace trim on linenEditor's Choice$48 – $72
Natori4.6

Natori Women's Feathers Contour Plunge Bra

Shallow, Petite & Close-to-Wide Set

Oatmeal blush four-way stretch knit wire-free scoop bra with wide ribbed bottom comfort bandMost Comfortable$22 – $44
Bali4.5

Bali Women's Comfort Revolution EasyLite Wirefree Bra

All-Day Wire-Free Comfort & Sensitive Ribs

Almond taupe molded memory-foam T-shirt underwire bra with flat laser-bonded side wings on stoneBest Value$32 – $50
Calvin Klein4.5

Calvin Klein Perfectly Fit Lightly Lined Memory Touch T-Shirt Bra

Invisible Smoothness Under Fitted Tees

What a 38A Actually Looks Like

A 38-inch band sits snugly around your ribcage just under your bust. Paired with an A cup, that means roughly a 1-inch gap between your underbust and fullest-bust measurement. Check the center gore first: if it doesn’t sit flat against your sternum, the cup is too small even if the band feels right.

Sister Sizes for 38A

If 38A isn’t quite right, the two closest sister sizes are 40AA (looser band, bigger cup, same volume) and 36B (snugger band, smaller cup, same volume). Every 2-inch band change pairs with exactly one cup-letter change in the opposite direction, because both numbers describe the same underlying volume.

38A in Other Sizing Systems

SystemBandCup
United States38″A
United Kingdom38″A
Europe (FR/ES/BE)115cmA
Italy115cmB
Japan/Korea95cmA

Fit Tips at This Size

The straps should need almost no tension to stay up; if you’re constantly tightening them, the band underneath isn’t doing its job. Sold out online?

Check the sister size first. It’s built to hold the same volume from a different band width and is worth trying before assuming the size doesn’t exist in that style.

Want your exact size instead of an estimate? Use the Main Bra Calculator- free, private, takes under a minute.

Common Mistakes at 38A

Buying based on the number alone without trying the style. Construction varies enough between brands that the same labeled size can fit two completely different ways.

Where to Actually Find This Size

Online shopping generally offers a wider real selection at this size than walking into a physical store, simply because warehouse inventory isn’t limited by shelf space the way retail floors are.

A Common Myth Worth Clearing Up

A common myth is that larger cup letters always mean an objectively “bigger” body overall. Cup size is about local volume relative to band size, not a measure of overall body size.

Style Recommendations for 38A

Full-coverage and plunge styles with real structure hold up better than soft, unlined designs at this range.

Why This Number Isn’t Permanent

Weight fluctuation of even a few pounds can nudge a band size, especially at the boundary between two sizes. This isn’t a flaw in the measuring process, just how bodies naturally vary.

Shopping Online at This Size

Reading recent reviews that mention true-to-size feedback for the exact style (rather than the brand generally) is one of the more reliable ways to predict fit before buying online.

Frequently Asked Questions

Round toward the snugger band if your ribcage is fuller, or the looser one if you find bands generally uncomfortable. Band comfort matters more than which number feels more familiar.
About the FitterChecked Across 7 Sizing Systems
Updated: November 2026
Written & Reviewed ByClaire Bennett• Bra Fit Educator & Founder

Claire Bennett spent over 10 years fitting women in specialty lingerie shops before starting Bra-SizeCalculator.com. She isn't a doctor, and she doesn't make up fake credentials. She shows the exact tape math behind every result so you can shop without guesswork.

10+ Years In-Store Boutique Fitting7 Global Sizing Systems CheckedUnsponsored Fit GuidesHow Our Sizing Works