Blog
How to Choose Bra Cup Type by Garment
Start with the garment, not a single spec
The right bra cup is defined by the garment it sits inside, not by one “best” number. A t-shirt bra needs a smooth, lightly padded cup that disappears under knits. A sports bra needs a firmer, high-support cup that holds shape through movement. A bralette needs a soft, flexible cup that moves with the body. This guide maps the most common garment types to the PU foam cup specification that actually performs — foam density, ILD hardness, mold type, and venting — so your sourcing decision starts from how the cup will be worn.
What every garment asks of a cup
Before matching specs, separate the three jobs a cup does:
- Support level — how much hold the garment promises (everyday comfort vs. structured or athletic).
- Smoothness under fabric — whether seams or texture will show through a tight knit.
- Flexibility — how much the cup should bend and breathe with the wearer.
Garment-by-garment cup specification
T-shirt & everyday bras
Use a molded PU foam cup at ILD 30–32, density 25–28 kg/m³, with 1.5–2 mm vent holes. Molded (not cut-and-sew) keeps the surface seamless so nothing reads through a fitted top.
Push-up & padded bras
Step up to ILD 33–35, density 28–30 kg/m³, for a structured cup that lifts and holds shape. The one-piece mold gives the clean, round profile these styles depend on.
Sports bras
High-support builds want ILD 33–35, density 28–30 kg/m³, with full venting for breathability during wear. Consistency across a large run matters more here than anywhere else.
Bralettes & wireless styles
Go softer: ILD 28–30, density 25–27 kg/m³, a lighter molded or flexible foam that bends with the body rather than holding a rigid shape.
Shapewear & corsetry
Firmer control calls for ILD 34–35, density up to 30 kg/m³, to keep architecture stable under compression.
Why molded PU foam fits most garment types
For 90% of bras made at scale, a molded PU foam cup is the default: it is one piece, seam-free, and repeatable batch after batch. A large existing mold library means most shapes are already tooled, so sampling is fast. At Senfeng, the standard molded PU foam range is density 25–30 kg/m³ and ILD 28–35, vented 1.5–2 mm per cup — values that cover t-shirt, push-up, sports, and bralette programs without re-engineering.
Spec-to-garment quick reference
| Garment | ILD | Density (kg/m³) | Cup type |
|---|---|---|---|
| T-shirt / everyday | 30–32 | 25–28 | Molded, seamless |
| Push-up / padded | 33–35 | 28–30 | Molded, structured |
| Sports | 33–35 | 28–30 | Molded, vented |
| Bralette / wireless | 28–30 | 25–27 | Soft molded |
| Shapewear | 34–35 | ~30 | Molded, firm |
Confirm before you order
Once the garment defines the spec, the practical questions are sampling speed and minimums. At Senfeng the bra cup MOQ is 500 pairs; if your shape matches one of 2,000+ existing molds, sampling takes 1–2 days, and a new mold 3–7 days — about 50% faster than the industry norm. Peak-season capacity can be locked 60 days ahead. Every batch ships with ILD and density data, and the factory holds OEKO-TEX Standard 100, GRS, and ISO 9001, with an 8-year export record and zero bad debt.
Related reading
Browse the full range of molded PU foam cups and request a sample: Senfeng Bra Cup products.
FAQ
What ILD is best for a t-shirt bra?
ILD 30–32 with density 25–28 kg/m³ gives light support and a smooth, seam-free surface that does not show through knits.
Can one mold serve several garment types?
Often yes — if the cup shape matches, ILD and density can be tuned within the foam grade to shift a cup from everyday to structured feel.
What is the MOQ for a custom cup?
500 pairs at Senfeng; existing molds sample in 1–2 days, new molds in 3–7 days.
Contact us directly: WhatsApp +86 137 1289 0858 | Website: sf-bracup.com