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How to Measure Bra Size

There are a handful ways to measure your bra size, however, none involving only tape measure will give you the exactly size. We at FinallyBra do not even believe there is a fixed and so called "accurate" bra size for anybody. The reason? Well, the bra is the most intimate piece on you and it needs to be PERFECTLY FIT! That means the bra needs specifically fit you, who is unique and different than everyone else. So the real accurate size for you depends on a lot of factors: the shape and firmness of your breasts, the width of your shoulder, the dimension of your chest, and the length of your torso etc. To make things more complicated, sizes vary vastly among different styles of bras and bra manufacturers. So the best way to find a perfectly-fit bra is to find your base size according to the following guide, from there you go up or down to find the one that fits you the most.

Important notes:

1. The bigger the breasts size, like 38D and larger, the more likely the base size measured according to the following guide (traditional band and bust size method) needs to be adjusted, like going up band or cup size;

2. The size of the bra you are wearing now does not necessarily mean it is your size. It is highly recommended you re-measure yourself every half year to factor in your body changes.

How to measure your bra size     

You can follow the tutorial in the video or written guidance below.

1. Determine your band size

Standing straight and staying relaxed ( you can  wear a non-padded underwire bra, no minimizer bra please), measure around your back, underneath your armpits, and just under your bust. Please keep the measuring tape parallel with the ground and not binding. Please round the measurement to the nearest whole number.

How to measure your bra size | bra sizing FinallyBra


Note: for better measurement, please bend your body forward 30 degree if you are thin, otherwise bend forward 30 to 45 degree. If the breasts are droopy, please lift the breast tissue to measure the band size.

Get your band size according to the following chart:

US band measurement (inch) convert to band size
Band measurement (inch) 27 28 29 30 31 32 33 34 35 36 37 38 39-40 41-42 43-44
Band size 30 30 32 32 34 34 34 36 36 36 38 38 40 42 44

If your band measurement is greater than 38 inch, your band size is the closest higher even number to your measurement. Say if your band measurement is 41 inch, then your band size is 42; if your band measurement is 40.75 inch, then the band size is 42.  

2. Measure your bust size

Measure around your back and underneath your armpits at the fullest part of your bust (at the nipple level). Please keep the measuring tape parallel with the ground and not binding. Please round the measurement to the nearest whole number.

3. Calculate your bra size

Subtract your band size (step 1) from your bust size (step 2), for each inch difference, the cup size increases one size, see the following chart:

US cup size A B C D E (DD) F(DDD) G(DDDD) H
Difference (inch) = Bust measurement - Band size 1 2 3 4 5 6 7 8



  • Step 1: 36" under measurement = 38" band size
  • Step 2: 40" over measurement
  • Step 3: 40" - 38" = 2" or B Cup Size
  • Your Size is probably a 38B

Note: The cup size calculation starts getting inaccurate at 4 inches larger than your band size. If you have pendulous breasts, your measurement will most likely be inaccurate.