Is 38B a Big Bra Size? Comfort, Shape & Sister Size Advice
38B combines a roomier band with a modest cup, delivering comfortable coverage for fuller ribcages.
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
Run through these inch measurements to double-check a 38B fit on fuller ribcages.
| 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. |
| Band-to-bust difference | ≈2 in | Subtract the snug band from the standing bust to verify the moderate B-cup difference. |
| Approx. cup depth | 8.5–9.0 in | Measure from the underwire base to nipple on a well-fitting bra to confirm cup depth. |
- 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.
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.
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.
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
- 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.
Common 38B questions
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.