The BRABAR Fit Dictionary: Every Bra Fitting Term Explained

Bra fitting has its own vocabulary, and a lot of confusion comes down to not knowing what a term actually means. This is a plain-language reference for every important bra-fitting term, from the basics to the more technical construction details.

Sizing Terms

Band size

The number in a bra size, measuring the circumference around the rib cage directly under the bust. The band provides roughly 80% of a bra's actual support.

Cup size

The letter in a bra size, representing the difference in inches between the band measurement and the bust measurement. Cup size is always relative to band size, not a fixed volume on its own.

Overbust measurement

The measurement around the fullest part of the bust, used together with the band measurement to calculate cup size.

Sister sizing

A different band-and-cup combination that holds roughly the same actual cup volume as your true size. Moving up one band size and down one cup letter (or the reverse) preserves that volume. Useful as a short-term bridge, not a substitute for your true measured size.

Plus-four method

An outdated measuring approach that adds four inches to the underbust measurement before determining band size. This inflates the band and distorts the resulting cup letter, and is not the method BRABAR uses.

Armpit method

A measuring approach that takes the band measurement higher on the torso, near the armpits, rather than directly under the bust. Like the plus-four method, this tends to produce an inaccurate band size.

Construction Terms

Gore

The center panel of a bra, between the two cups. On a properly fitting bra, the gore sits flat against the sternum rather than floating away from the body.

Underband

Another term for the band itself, the horizontal piece that wraps around the rib cage below the cups.

Underwire

A rigid, usually U-shaped support piece sewn into the bottom of the cup on structured bras. Despite the name association with support, the underwire primarily affects cup shape; the band still does most of the actual supporting work.

Encapsulation

A support method where each breast is held in its own individually structured cup, rather than compressed against the chest. Encapsulation is generally considered more effective than compression alone for a fuller bust or for high-movement activity like running.

Compression

A support method that flattens breast tissue against the chest as a single unit, rather than shaping each side individually. Common in simpler sports bras; less effective than encapsulation for a fuller bust specifically.

Apex

The point of fullest projection on the bust, used as a reference point for where a cup should be shaped to fit correctly.

Wing

The side portion of the band, between the cup and the back closure. A wider wing generally offers more side coverage and support.

Fit-Problem Terms

Cup gapping

Empty space between the cup and the breast, usually meaning the cup is too large for your shape.

Spillage

Breast tissue extending beyond the edge of the cup, at the top or sides, usually meaning the cup is too small or too narrow.

Back bulge

Tissue pushed up above or down below the band at the back, usually caused by a band that's too tight or sitting too high.

Quad boob

A visible double-bulge effect at the top of the cup, typically caused by a cup that's too small for the actual breast volume.

Side boob

Breast tissue visible at the side of a garment, which may be a style choice (in a low-side-coverage design) or a fit issue (if the cup doesn't provide enough side coverage).

Style Terms

Bralette

A soft, typically wire-free bra style with minimal structure, often without padding. Lower support than a structured everyday bra, generally better suited to light activity or lounging.

Longline

A bra style with an extended band that reaches further down the torso than a standard bra, offering more coverage and often more support through the extra band length.

Racerback

A strap configuration that converges into a single point at the back, in a Y or T shape, rather than two parallel straps. Helps prevent strap slipping, particularly for sloped shoulders or during activity.

Convertible straps

Straps designed to be reconfigured into multiple positions, such as standard, crossback, or halter, using the same garment.

A Note on Underwire and Health

A persistent myth claims underwire bras cause breast cancer. This has been examined and disproven; no credible scientific evidence supports a link between underwire bras and cancer risk. The real reasons to consider a wire-free style are comfort and flexibility, not an unfounded health claim.

Frequently Asked Questions

What is the gore of a bra?

The center panel between the two cups. On a properly fitting bra, it sits flat against the sternum.

What's the difference between encapsulation and compression?

Encapsulation holds each breast in its own structured cup; compression flattens breast tissue against the chest as a single unit. Encapsulation is generally more effective for a fuller bust or high-movement activity.

What is sister sizing?

A different band-and-cup combination that holds roughly the same cup volume as your true size, useful as a short-term bridge but not a substitute for your actual measured size.

Do underwire bras cause cancer?

No. This is a persistent myth with no credible scientific evidence behind it.

What does quad boob mean?

A visible double-bulge effect at the top of the cup, typically caused by a cup that's too small for the actual breast volume.

Find your true size with BRABAR's Fit Guide and Bra Size Calculator, or explore the full BRABAR collection.