How do I calculate my correct bra size?

First, measure your underbust (directly under the bust) tightly. If in inches, round to the nearest whole number; if it is even, add 4, if it is odd, add 5 to find your Band Size. Second, measure your bust (fullest part) loosely. The difference (Bust minus Band) determines your Cup Size (e.g. 1" = A, 2" = B, 3" = C, 4" = D).

What is 32 34 36 in bra?

These numbers represent the Band Size of the bra, which corresponds to the ribcage circumference. For example, a band size of 34 is designed for someone with an underbust measurement of approximately 29 to 30 inches (when calculated using the traditional +4/+5 method).

Is 34B or 32C bigger?

They have the same cup volume! Bra sizes use 'sister sizing.' A 34B has the same volume of breast tissue as a 32C or a 36A. The difference is the band size (underbust tightness). If you drop a band size, you must go up one cup size to keep the same cup volume.

What is 80 cm bra size?

An 80 cm underbust measurement corresponds to an EU band size of 80, which translates to a UK/US/Indian band size of 36.

Bra Size Calculator

Determine your accurate band size, cup size, and find your sister sizing options across international systems.

Sizing Parameters

Your Standard Size

Calculated Size

34B

Band Size

Cup Size

Sister Sizes (Similar Cup Volumes)

Tighter Band: 32C
Looser Band: 36A

Accurate Bra Sizing, Band Calculations & Cup Dimensions

Find your perfect fitting bra size. Measure underbust ribcage size, analyze cup differences, and understand sister sizing volume rules.

Frequently Asked Questions

Measure your underbust ribcage. In traditional sizing, if it is even, add 4 inches; if odd, add 5 inches. Modern fitting practices also allow for direct band sizing matching the ribcage measurement.

Sister sizes share the same cup volume. If you drop a band size, you must go up a cup size to keep the cup volume identical (e.g. 34C sister sizes are 32D and 36B).

Different brands use varying manufacturing templates, fabric elasticities, and sizing charts. Treat your calculated size as a baseline to adjust up or down.

You should remeasure every 6 to 12 months, or after significant life events like weight fluctuations, hormonal shifts, pregnancy, or changes in fitness routines.

Underbust and bust measurements are universal. Sizing systems in the UK, EU, and US handle band labels and double-cup letters (like DD/DDD/F) differently.

An ill-fitting bra fails to distribute weight correctly, leading to neck strain, shoulder groove indentations, back pain, skin chafing, and poor posture.