How to Measure Bra Size in 4 Easy Steps


Is your bra the right size?

Besides not being the most comfortable piece of clothing, a bra is not a one-size-fits-all kind of item either.

That being said, it’s really important to know how to measure bra size properly.

Keep reading for signs that you’re not wearing a bra your size and the simple steps to determine the perfect bra size that will fit your body type, give you a better posture and more comfort, and make every outfit look even better as a bonus.

Signs You Are Not Wearing the Right Bra Size

According to different statistics, the probability that you’re wearing the wrong bra size is pretty high. Unfortunately, choosing ill-fitting bras is a common mistake women make.

This can cause bad posture, neck and back pain, and even breast pain, as well as sagging and marks on the skin due to too-tight bra parts.

You can be sure you don’t have the proper bra size measurements if you’re experiencing some of the following signs:

  • Your breasts are flowing out of the cups, or the cups have a gap
  • Your back band is riding up
  • Your bra straps are too tight or falling off
  • Wires are going over your breasts

Simply put, if you’re not feeling comfortable and confident wearing your bra, it’s probably the wrong size.

However, note that different breast shapes don’t fit the same with all bra shapes and brands, so you might have more than one size.

DID YOU KNOW: A correlation study on breast size, bra fitting, and thoracic pain in women aged 18-26 found that 70% of them wore bras that were too small, and 10% wore too big ones.

How to Measure Bra Size?

Wearing the right band and cup size can make a huge difference in how you look and feel.

To determine proper measurements and find a bra that fits in a few minutes, all you need is some measuring tape and a mirror. It’s also suggested that you wear your best-fitting unpadded bra. Just follow our simple instructions:

1. Determine Band Size

To do this, stand up straight and place the measuring tape where your bra band would go—around your rib cage, underneath the breasts. When taking your bra measurement, keep the tape leveled and not too tight, but not loose either.

Measure in inches and write it down. If you get an even number, add four, and in case you land on an odd number, add five.

When wearing your bra, you should be able to place two fingers underneath the band on the backside and move it approximately an inch away from your body. The band should fit horizontally all around your body, without leaving any marks on the skin when secured on the last hook. If this is as described, your measuring for bra size is properly done.

2. Determine Cup Size

The next step involves moving the measurement tape over the fullest part of your breasts, which is usually over the nipples, but this can vary depending on your breast shape.

The measuring tape should be somewhat loose, and you should write down the result in inches again.

When you take the measure for a bra, determine your cup size in the following way: subtract the result you got for your band size from the result measured around the fullest part of your breasts.

The difference in inches between these two measurements determines the cup size. If the difference is 0 then you’re an AA, if it’s 1 inch then you’re an A, 2 inches are a B, 3 inches equal C, and so on.

So, for example, if your measurement for band size is 36 inches, and you measure 38 inches around the fullest part of your breasts, then you’re a 36B.

3. Ensure Bra Straps Are Correctly Placed

After you measure bra size at home and try on the size that fits, make sure to adjust the bra straps. Skipping this step is a common mistake that may lead to the wrong conclusion that the bra isn’t fitting properly.

If the cups seem big, try to adjust the bra straps by making them shorter, and if the cups seem too tight, making the straps longer can make all the difference.

Straps should provide elasticity and not be loose enough to fall off or tight enough to leave marks on the skin or your shoulders.

4. Once Again, Look at Yourself in the Mirror

After sizing for a bra and trying one on, take your time determining if it’s a fit. Do you like what you see and how you feel when wearing this piece of underwear? Don’t forget that while bras should be supportive and comfortable, they should also look good and make your outfit fit better.

Key Takeaways

Wearing ill-fitting bras can cause problems like bad posture, or neck and back pain, and make you uncomfortable throughout the day.
If you have a gap in your bra or your breasts are spilling out of the cups, you have marks on the skin, or your band is riding up, you’re probably wearing the wrong bra size.
You can learn how to measure bra size at home, determine the proper band size and cup size, and choose the right fit using only a measuring tape and a mirror.
When choosing a bra, make sure to consider your body type, breast and torso shape, but also the brand you’re purchasing from because they can have different standards when it comes to sizes.

How Often Should You Measure Your Bra Size?

According to bra fitting experts, you should repeat the measurement process every 6 to 12 months. Some even suggest you do it every time you go shopping for a new bra, as the fulness of the breasts fluctuates due to different hormone levels or weight changes, and it’s especially emphasized during pregnancy and post-pregnancy periods.

Keep in mind that you might not be the same size when trying on different brands of underwear. This is where a so-called sister size may come in handy to determine a bra size that fits you perfectly.

Sister size is one band size smaller or bigger than your usual size, depending on whether the bra you’re trying on fits a little loose or a bit tight. The letter determining your cup is also different in your sister’s size.

If the band feels loose, you should try one band size smaller, but a cup size larger—say you’re a 38B, try on the 36C. If the band is tight, go for the 40A—a bigger band size, but a smaller cup.

The sister size may help when you’re loving a piece of underwear but can’t find it in your usual size, or when you’re shopping for a gift for a girlfriend and can’t find a fit.

DID YOU KNOW: Some lingerie brands have experienced bra fitting experts skilled at determining bra size for you by eye. As many women would be more comfortable with female bra fitting experts, this might even be one of the business ideas that are a perfect fit for women.


Hopefully, this article gave you some insight in how to determine your band and cup size, avoid ill-fitting bras, and arm yourself with confidence.

Make sure to have a measuring tape handy before you go on a shopping spree looking for new underwear because your bra size may fluctuate due to hormonal status, weight variations, and other factors.

Different brands can also use different standards, so be sure to try on your sister size as well.


How do I calculate my bra size?

You can do this at home simply by using a measuring tape and following the steps provided in this article. Apart from determining your band and cup size, you should also find out what your sister sizes are and how you can use them when purchasing a new bra.

What size is a 34A bra?

If your usual bra size is 34A and you can’t find it for a piece you love, you can avoid making a mistake by using sister sizes to determine which would fit you best. A sister size up for 34A would be 36AA, and a sister size down would be 32B.

What is the difference between 34B and 32B?

The difference between 32B and 34B is in the band size—a 32B is smaller than 34B when it comes to their band sizes, and the cups are also different because a cup volume grows bigger with the size.
To determine which band and cup size are the best fit for you, it’s important to know exactly how to measure bra size following the steps provided in this article.

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