Bra Size Calculator - Find Your Bra & Size

There are two stages to measuring your bra size. Firstly, you measure under your bust to find what's call your band size and then you have to determine your cup size in order to get the best fitting bra.

Remember that there is no such thing as a definitive bra size as styles and cuts vary between products and manufacturers so please the following approach as a guide to your size.

How to find your bra size measurement?

Using a soft tape measure, measure your ribcage just under the bust. To get an accurate measurement make sure you are wearing a non-padded bra and the tape is straight front and back then use the chart below to obtain your bra size


28-29  30-31 32-33 34-35 36-37 38-39 40-41 42-43 44-45  46-47 

Bra Size

32 34 36 38 40 42 44 46 48 50

How to find your cup size?

Measure with a tape measure your bust where it is at its fullest and round up to the next whole number (e.g. I f the bust measures 37.5 inches, round that up to 38 inches).

To obtain your cup size deduct band size. The table below will then convert your measurement to get the correct band size for you.

    Bust - Band Size Difference        Cup Size      
1/2" AA
1" A
2" B
3" C
4" D
5" DD OR E
6" F
7" GG
8" H
9" I
10" J

Working example:

Rib cage measurement is 31.3 so round up to 32 and add 3 inches = 35. This then needs to be rounded up to 36 for the band size.

Bust measurement is 39 so deduct the band size from the bust measurement 39-36 = 3 and from the chart above, cup size is a C.

Please note that most sports bras are cut differently so these charts should be considered a guide and please contact us if you have any questions.

We have produced a short video to help you get the right fitting sports bra

Choosing the right sports bra

Getting a bra that fits properly is always important, but when it comes to investing in a sports bra, this becomes even more important because strenuous activity will of course cause your breasts to move (up to 10cm during exercise). This therefore requires the proper support and protection from a bra that fits correctly, which can be found by using the Boobydoo bra size calculator.

An average bra cannot provide these high levels of protection during exercise as they are not designed for the job, only reducing breast movement by 35%. An insignificant number when compared to the 80% of reduced breast movement the right style and fit of sports bra will provide you with. However, the question remains – how do you gain the right fit and know which style is right for you?

We can't emphasise enough the importance of wearing a good fitting sports bra to ensure you can both enjoy your sport to the max and protect your breasts for the future.

During exercise women's breasts can move up to 10 cm, to make up for this lack of natural support you should wear a sports bra.

As there are no muscles in your breasts, without the right support they will bounce during exercise. Normal bras reduce breast movement by around 35%, but a good fitting sports bra achieves up to 80% reduction in movement thus giving you added protection and comfort. Padded sports bras can also provide an extra level of comfort and protection.

What type of sports bra should I use?

The type of sports you use will depend on the type of exercise or sports you participate in.

Fundamentally you are looking for the right blend of support (bounce reduction) , comfort and appearance.

Today, there are an increasing number of products styles and colours available. So we would encourage you to try some different types until you find the best one for you.

What level of impact bra will I need?

Different sports bras are designed for different levels of activity and impact so use the chart below to help identify the level of impact you require.

Tip for the larger cup sizes: You may be better served moving up one level of impact to give you best support

By using the Impact Search capability on the Home Page, select the relevant Impact level and it will bring forward all the relevant sports bras for your activity. For a list of high impact sports bras, have a look at our high impact sports bra page.

Level of Impact Sports/Activities
Maximum Impact Running, Hockey, Basketball, Gymnastics, Volleyball, Equestrian, Triathlon, Football, Rugby, Netball, Squash,
High Impact Tennis, Skiing, Martial Arts, Gym Classes, Circuit Training, Zumba
Medium Impact Rowing, Cycling/Spinning, Dance
Light Impact Yoga/Pilates, Dance (light), Walking

Now that you have found the right style for your exercising needs, it is essential that you choose the right size or the bra will not perform how it should and could even lead to increased pain and discomfort. Gone are the days of guesswork, as all you need to do now is use our bra size calculator!

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