Understanding Bust Size and Cup Size: The BRABAR Guide

Bust and cup size are the two measurements that actually determine bra fit, and getting them right removes most of the guesswork from bra shopping entirely. Here's how the measurements work, what they mean, and how to shop with them once you have them.

Measuring Bust and Band Size

Two measurements are all it takes. Wrap a soft tape directly under the bust, level all the way around, for band size, and round to the nearest even number. Then measure around the fullest part of the bust for the bust measurement. See BRABAR's rib cage measuring method for the full walkthrough.

From Measurements to Cup Size

Subtract the band number from the bust number — the difference in inches gives the cup letter. A 1-inch difference is an A cup, 2 inches a B, 3 inches a C, 4 inches a D, 5 inches a DD/E, and 6 inches a DDD/F. The same cup letter means something different on different band sizes, since cup volume is relative to the band it's paired with — a 28D and a 34D don't hold the same amount of breast tissue.

Shopping With an Accurate Size

Once the size is confirmed, style choice becomes the easier part. A soft, wire-free everyday bra covers daily wear; a cami bra top works as a layering piece or standalone top; a properly fitted strapless bra handles open-shoulder or strapless necklines; and a halter style provides support under backless or plunging necklines without visible straps. BRABAR's core range covers bands 28 through 38 and cups AA through DDD/F, built specifically around proportions many mainstream brands don't stock well.

Re-Measuring as Bodies Change

Growth, weight changes, hormones, pregnancy, and simply time can all shift bra size, sometimes more than once across a life. Re-measuring rather than assuming an old size still applies is the practical response at any stage, not a sign anything went wrong.

Frequently Asked Questions

How do I measure my bra cup size?

Measure the rib cage directly under the bust for band size, and the fullest part of the bust for the bust measurement. Subtract the band number from the bust number — the difference in inches gives the cup letter.

Does the same cup letter mean the same size on every band?

No. Cup volume is relative to band size, so a 28D and a 34D hold different amounts of breast tissue even though they share the same letter.

How often should bra size be re-measured?

Periodically, and any time a bra stops fitting well — growth, weight changes, hormones, pregnancy, and time can all shift size, sometimes more than once across a life.

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