Fact Checked

How do I Determine my Bra Cup Size?

Emma G.
Emma G.

Wearing a bra that does not fit correctly can lead to posture problems, back pain, and general discomfort, yet surveys show that many women regularly wear the wrong size bra. Determining the correct bra cup size for you is an easy procedure that can be done at home or by a trained sales clerk. To measure for bra cup size, you need a measuring tape from a sewing kit and some basic math. You will take two measurements, and when taking these measurements, you should be wearing the best fitting bra you currently own. It should not be a sports bra or minimizer bra, as this will result in measurements that are smaller than your actual size, nor should it be a padded bra or push-up bra, as this will lead to measurements larger than your actual size. Measurements tend to be most accurate when taken by someone else, so try to get a friend to help you.

Measure your band size first because you need this to figure out your bra cup size. Start by standing up straight and breathing as much air as possible out of your lungs. Then wrap the measuring tape around the band of the bra directly under the bust. Check that the tape is parallel to the floor to get the most accurate measurement.

A woman trying on a bra.
A woman trying on a bra.

Round the resulting number up or down to the nearest inch. Bra bands come in even-numbered sizes only, so if your rounded measurement is an odd number, add 5 to it. Otherwise add 4. For example, if your measuring tape reads 31.6, you would round up to 32 inches and then add 4. Your band size would be 36.

For the second measurement, stand straight with your arms at your sides. Wrap the tape measure around your back and over the largest part of your breast. Be sure the tape stays parallel to the floor. The tape measure should also be tight against the skin without squeezing. Round the resulting measurement up or down to the nearest inch.

A sports bra.
A sports bra.

With these two measurements, you will be able to determine your bra cup size. Take your band size and subtract it from the bra cup measurement. The difference between these two numbers is your cup size. If the difference is between half an inch and 1 inch, you are an A cup. If it is 2, your are a B, and so on.

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Discussion Comments


@umbra21 - If in doubt go to a good bra store and get measured. Most higher-end department stores will do this as well. Don't settle for someone who doesn't seem to know what they are doing, or is trying to sell you something expensive.

A good bra fitting can make all the difference between good posture, or bad posture and can prevent you from suffering from back pain or embarrassment from bra malfunction.

Once you've got the sizes figured out, regularly revisit them, because you will change over time. Your bras also simply won't last all that long and need to be updated. That's why they have multiple catches in the back. It's so that you can tighten the band as it gradually wears out.

Finally, you might end up needing different sizes for different kinds of bra. A strapless bra, for example, might possibly need a tighter band size and a shelf bra might need a larger cup size. Trying on your bra, underneath the clothing you intend to wear with it, is essential.


@clintflint - My tip is that it's always better to go one size higher with the cup if your breasts are slightly lopsided in size. This is true of most women, so don't worry if they are (unless the size difference has occurred suddenly or is extreme).

Go up to the size of the larger breast and then, if necessary, use a pad to fill out the other cup. You can also get custom bras made that will have this built into them, but they can be very expensive.


When trying on a new bra in a store, make sure you don't rush and get something that only fits for the first few minutes.

Jump a few times and bend forward so that your chest moves around and you can see what happens with the cups. It may also be a matter of getting the right band size as well.

Also, make sure you wear something that you know will show up problems with your bra. Generally a t-shirt is the best bet, in my experience. Sometimes you can't tell the bra cup sizes are too small until you see the shape they make under a shirt.

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      A woman trying on a bra.
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