Understanding 38B Bra Size
A 38B bra size is considered a medium band size with a moderate cup size. This size is perfect for people with an average frame and moderate breast volume. Let's explore what makes this size unique and how to find the perfect fit.
Is 38B a Big Bra Size? Comfort, Shape & Sister Size Advice
Fast facts about 38B
- Band 38 suits snug underbust measurements around 36–37 inches.
- B cups equal roughly a 2 inch difference between bust and band—moderate volume on a wider frame.
- The broader band spreads support, so the size reads balanced rather than large.
- Sister sizes 36C and 40A keep cup volume similar when you need to adjust the band.
How 38B is measured
Band fit
Aim for a 36–37 inch snug underbust so the band anchors firmly without cutting in.
Cup depth
B cups reflect about a 2 inch difference—roughly 40 inches at the fullest point.
Support expectation
Look for supportive wings, cushioned straps, and side boning to stabilize the wider band.
38B bust size in inches
| Measurement | Typical inches | How to capture it |
|---|---|---|
| Snug band (ribcage) | 36–37 in | Measure firmly around the ribcage on an exhale, then round to the 38 band label. |
| Standing bust | 39.5–40.5 in | Keep the tape level across the fullest bust point while standing naturally. |
| Approx. cup depth | 8.5–9.0 in | Measure from the underwire base to nipple on a well-fitting bra to confirm cup depth. |
| Band-to-bust difference | ≈2 in | Subtract the snug band from the standing bust to verify the moderate B-cup difference. |
38B bust size in centimeters
| Measurement | Typical cm | How to capture it |
|---|---|---|
| Snug band (ribcage) | 91–95 cm | Measure firmly around the ribcage, then map it to EU 85 / FR 100 / JP 85 band sizes. |
| Standing bust | 100–103 cm | Keep the tape level across the fullest point while standing upright and relaxed. |
| Approx. cup depth | 22–23 cm | Measure from the underwire root to the apex on a supportive bra to ensure the cup height matches your shape. |
| Band-to-bust difference | ≈5 cm | Subtract the snug band from the bust to confirm the two-inch B cup depth in metric terms. |
- Leaning bust readings around 41 in show you have enough tissue for full coverage.
- If your bust measures closer to 39 in but the band feels slack, try the 36C sister size for added support.
- When snug band numbers creep past 37.5 in, move to 40A for more breathing room while keeping similar cup volume.
- Metric conversion: 38B typically aligns with 91–95 cm underbust and 100–103 cm bust measurements.
38B inch quick reference
- 38B ≈ 38 band label, 40 in bust, two-inch cup difference.
- Sister matches: 36C if you need a tighter band, 40A if you prefer more ease.
- International equivalents: EU 85B, FR 100B, UK 38B, JP 85B.
Wide bands stretch over time—reassess measurements every few months to maintain support.
38B across popular sizing systems
Match US 38B to the most searched regional labels without leaving this guide.
Currently showing the United States (US) label — copy 38B to match tags instantly.
United States (US)
38B
United Kingdom (UK)
38B
Europe (EU)
85B
France (FR)
100B
Japan (JP)
90B
Australia (AU)
16B
Quick converter
Switch systems and copy the exact label for checkout forms or bra tags.
Need step-by-step help? Jump into the dedicated guides below for measurement nuances and shopping tips.
Perfect For
- Average frames
- Medium ribcages
- Moderate breast volume
- Balanced proportions
Recommended Styles
T-Shirt Bras
Perfect for everyday wear under fitted clothing
- Seamless
- Molded cups
- Comfortable
Balconette Bras
Great for creating a natural lift and shape
- Wide-set straps
- Lower cut cups
- Enhancing
Plunge Bras
Ideal for low-cut tops and dresses
- Deep V-neck
- Minimal coverage
- Versatile
How 38B tends to look
Because the cup volume is moderate, the overall profile appears smooth and natural.
- T-shirt bras keep the front sleek under everyday tops without extra bulk.
- Lightly lined wireless bras emphasise comfort while maintaining shape.
- Side-smoothing styles help prevent tissue from shifting toward the underarm.
- Choose sports bras with a firm underband to keep the wider frame supported during movement.
38B compared with nearby sizes
Here’s how 38B relates to the sizes fitters see shoppers switch between most often.
- 38A is one cup shallower when you prefer a subtler profile or notice cup wrinkling.
- 38C keeps the band but increases depth for fuller coverage.
- 40A extends the band for more ease while keeping a similar cup volume.
Sister size playbook
- Switch to 36C if the band feels loose even on the tightest hook.
- Move to 40A when the band digs in or you want extra breathing room.
- Test 38C if you need more cup coverage without changing the band.
Fit checks before you buy
When trying on 38B bras, look for these key fit indicators:
- The band should fit snugly around your ribcage
- Cups should fully contain your breasts without spillage
- Straps should stay in place without digging in
- The center gore should lie flat against your chest
- Ensure the band is level—most of the support should come from it, not the straps.
- Look for padded or wider straps to spread weight across the shoulders.
- Check the center gore; it should rest softly against the sternum without floating.
- Opt for three-row hook-and-eye closures for durability as the band stretches over time.
Remember that fit can vary between brands and styles. Always try on bras before purchasing to ensure the perfect fit.
Common 38B questions
What size is 38B in other systems?
38B converts to 38B in UK sizes, 85B in EU, 100B in FR, 90B in JP, and 16B in AU.
Is 38B considered a large size?
It carries moderate cup volume. The wider band prioritises comfort and stability rather than making the bust look bigger.
What should I try if 38B feels loose?
Start with the 36C sister size. You keep similar cup space but gain a firmer band for support.
How can I stop cup gaping at the top?
Look for bras with stretch lace or memory foam cups, and scoop tissue into the cups to fill the upper edge.
What is the bust size for 38B in inches?
Aim for a snug 36–37 inch ribcage measurement (rounded to a 38 band) and about 39.5–40.5 inches at the fullest bust. That near two-inch difference maps to a B cup, though band stretch and posture can shift the reading slightly.
Get comfortable in 38B
Confirm your measurements, read the step-by-step size guide, and explore perception tips to style the size your way.