How We Measure Up

Your unique shape, size, and breast tissue density will influence your bra fitting experience. The measuring process is designed to guide you to a starting band size and cup size. From there, it's important to try on different styles to find the best fit for you.
To Ensure the Most Accurate Measurement:
  • Visit a fitting professional or recruit someone else to measure you.
  • Wear a natural-fitting lingerie bra that maintains your natural shape—with little to no padding or minimizing features.
  • Breathe deep and stay relaxed.
1. Rib Cage Measurement

Measure around your rib cage around the bottom band, just under the breast. The tape measure should feel quite snug. Round the measurement down to the closest inch.

2. Band Size Conversion

Using our measurement guidelines below, find your corresponding band size based on your rib cage measurement.

3. Bust Size Measurement

Measure the bust over the fullest point of the breast. For larger-breasted women, the fullest point may not be at center, and is often lower. As breast tissue can fluctuate as much as 20%, round up to the closest inch.

4. Cup Size Conversion

Subtract your actual rib cage measurement (step 1) from your actual bust measurement (step 3). The difference in inches is your suggested cup size. If the difference is between sizes, round up to the larger size.

Bottom Band

Measurement Guideline

Rib Cage Band Size
25"-27" 30
27"-29" 32
29"-31" 34
31"-33" 36
33"-35" 38
35"-37" 40
37"-39" 42
39"-41" 44
Cup Size

Measurement Guideline

Difference in Cup Size Your Cup Size
3" AA
4" A
5" B
6" C
7" D
8" DD
9" E
10" F
37 - 30 = 7"

Bust size minus rib cage size=cup size

Size = 34D

Four Fundamentals of Fit

Unsure how your sports bra should look and feel?
Gain confidence with these checkpoints.
1. The Band

On the middle hook, ensure it's snug and lies even. If it rides up, it's too loose and/or the straps need adjustment. Chafing can occur if the band is too loose.the band is too loose.

2. The Cups

Scoop your breasts into the cups, ensuring they are centered. The breast tissue should be fully contained, but the bra doesn't pucker or wrinkle. Anything that spills out the top or side indicates the cup size is too small.

3. Underwire

If applicable, make sure it sits flat against the body. Any gaping indicates the need to go up a cup size.

4. The Straps

They should not slip or dig. Adjustable straps can offer a more custom fit. If the support feels like it's coming from the straps, you may need a smaller band size.

Get the Bra You Deserve

Every woman deserves to feel perfectly supported.
Here are some common challenges and our suggested solutions.
Surgery or Injury

Women who have suffered an arm, neck, or shoulder injury, or who have just had breast surgery, may find a traditional racerback style too hard to put on. Look for a style that has detachable front-adjustable straps, or an open-back style with a back closure.




Pregnancy or Nursing

Sports bras are a great solution for the extra sensitivity women may experience during pregnancy or nursing. Look for a style with front-adjustable straps that can adjust with your changing body. Plus, those front-adjustable straps can make it easier to breastfeed.



Narrow Shoulders

Even with a well-fitted sports bra, some women experience straps that continuously slip off the shoulders. Keep straps in check a racerback or crossback style.




Uneven Breasts

Most women have one breast larger than the other. Always fit your sports bra to the larger cup and look for a style with adjustable straps that allows you to customize the fit to each individual breast.



Wearing Two Bras

Women who wear two bras while running are not getting the fit, support, or comfort they need. Look for a supportive style designed for larger cups. Sometimes one is better than two!




The Bra Standard

The Brooks Collection is the #1 sports bra brand with runners and for good reason.

A great sports bra is at the center of every woman's run. It's why our expert team of designers and engineers take pride in their craft--building bras to fit women, not forcing women to fit the bra.

Their dedication to testing and editing ensures every stitch of the final product is purposeful and its beauty is matched with proven performance. Women who discover what running feels like in our bras know why we are the best in the industry. We invite you to experience the difference a bra can make.