Measure your rib cage

Wrap a measuring tape around your rib cage, just above your breast and under your armpits. Breathe in and out. Bend and rotate your torso. Loosen the measuring tape until you are comfortable, while keeping your finger on the tape to mark the measurement. Write this number down.

Measure your bust

Wrap the measuring tape around the fullest part of your bust, keeping your finger on the tape to mark the measurement. Write this number down.
Proper Fit = Proper Posture
Choosing the right size is vital to getting great results. If the size is too small or too large, the Etalon straps won’t be able to guide your posture with a gentle pull. If your perfect fit is between sizes, we suggest sizing down for a more compressive fit, or sizing up for a more relaxed fit.

CUP SIZE CHART — subtracting rib your cage circumference from your bust.

1 inch 2 inches 3 inches 4 inches 5 inches

BRA SIZE CHART — the number represents your rib cage circumference, the letter is your cup size.

Bra size 30A - 30A
30D - 30E
32A - 32B
32D - 32E
34A - 34C
34D - 34E
36A - 36C
36D - 36E
38A - 38C
38D - 38E
40A - 40C

Size Guide

Factors that might affect bra fit & comfort

Your Cycle.
During your period, your body wants to retain fluid so the breasts swell. Swelling can cause potential discomfort while wearing the posture bra. If the bra gets too uncomfortable, take a break from wearing it until your period ends.

Covid Vaccine/Boosters.
After taking a Covid vaccine, your lymph nodes might swell and cause incredible discomfort while wearing a posture bra. It happened to our founder! Take a break from wearing the bra until your lymph nodes normalize.

If you're still unsure about your size or you haven’t found your size, drop us a line at and we'd be happy to help.