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How to Measure Your Bra Size: A Step-By-Step Guide

How to Measure Your Bra Size: A Step-By-Step Guide

Surveys show that the majority of people wearing bras are wearing the wrong size. That’s probably because most of us were never taught how to measure bra size. If you were lucky, a parent took you to get fitted for your first bra. From then on, it’s mostly been guesswork.

You know your size (roughly), you like the look and feel of a bra, and that’s enough to put it in your shopping basket. But this is not how it should be. Knowing your correct bra size is extremely important before you go bra shopping. 

How do you measure your bra size correctly? Do you need a professional bra fitting? Or can you do it at home with a tape measure?

The answer is you can absolutely do it at home. Indeed, the best gift you can give yourself today is to perform an accurate bust measurement and make sure your bra fits properly.

Continue reading for a step-by-step guide on how to measure bra size. I’ll talk about the different bra styles like strapless bras and sports bras. And last but not least, I’ll tell you why bust measurements are so important. 


Why Is A Well-Fitted Bra Important?

Featured Product: KFT Goddess Bra in Brightest Red

Slipping straps and gaping cups can be annoying, but aside from being uncomfortable, a poorly fitting bra is also a health hazard.

Wearing the wrong bra size can cause or worsen neck, shoulder, and back pain. It can also cause issues like poor posture and breast sagging.

This is because bras support the breasts. Without the proper support, the breasts can sway up to 4 cm even while you’re doing something as simple as walking (crazy, right?).


How Do Experts Measure Bra Size?

Many lingerie brands no longer use tape measures. Their experts can do it by eye. 

Sounds impressive, right?

In the store or online, expert fitters can look at you in your current bra (preferably one that you find particularly comfortable) and tell you, for example, to go down a cup for a better fit. 

But while specialists are not picking up a tape measure anymore, if you are going to measure your bust at home, you will need one. 


How To Measure Bra Size At Home With A Measuring Tape?

Before you go shopping for a new bra, learn how to measure bra size. It’s a small investment of your time but it will help you find a bra that fits perfectly.

Here’s a step-by-step guide to bust measurement at home.

First things first -- make sure you’re wearing a comfortable, lightly lined or non-padded bra (full coverage bras are best), and keep a measuring tape handy. 


How To Measure Bra Band Size

  1. Wrap the measuring tape around your torso, right below your bra band and directly under your bust.
  2. The tape should be snug, but not pulled so tight that it’s uncomfortable.
  3. Make sure the measuring tape is at the same level all around when you measure your band.
  4. Note down the inches. If it is an even number, this is your calculated band size. 
  5. If it is an odd number, round off to the nearest even number. This is your band size.


How To Measure Bra Cup Size

  1. Place the measuring tape around the fullest part of your chest.
  2. The tape should sit flat and level. 
  3. Note down how many inches. This is your cup size.


How To Calculate For Bra Cup Volume

  1. Subtract your band size from your cup size.
  2. Make a note of the difference in inches.
    1. 1 inch difference = A cup
    2. 2 inches difference = B cup
    3. 3 inches difference = C cup
    4. 4 inches difference = D cup, and so on.


If your band size is 35 inches and your cup size is 36 inches, the difference is 1 inch. This means you have an A cup bust. If your band size is 35 inches and your cup size is 38 inches, the difference is 3 inches and you have a C cup. 


How To Determine Your Actual Bra Size

Take your band size and your cup size and put them together to get your bra size for the right fit. 

For instance, if your band size is 36 inches and your cup size is 38 inches, the difference is 2 inches. This means you have a B cup and your bra size is 36B.

Now all you need to do is check the bra size chart on your favorite lingerie brand labels and pick up the right one for your bust size.


How To Measure Bra Size For A Sports Bra?

Experts in women’s health say that unsupported breasts can move up to 14 cm during vigorous exercise.

Yes, that’s right... 14 cm!

If you don’t wear a well-fitted sports bra you could suffer permanent damage to the Cooper’s ligaments that hold your boobs in place. So, finding the right size in sports bras is equally important. 

Your sports bra size is practically similar to your regular bra size, however, you must consider your level of activity when picking a sports bra.

 Featured Products
Top - KFT Freedom Bra in Inky Black
Bottom - KFT Keep Moving Lined Shorts in Pineapple Party

Generally speaking, low-impact sports bras support A to B cups, while fuller cups (C to D) might need more support from medium-impact sports bras. If you have bigger than D cups, you’ll need a high-impact bra to make sure you’re breasts are fully supported during your workout.


Is Sports Bra Size The Same As Regular Bra Size?

For the most part, yes!

But it can be a little more complicated than just reaching for your regular bra size.

Sports bras vary depending on the type of physical activity they are designed for, ranging from low impact to medium impact and high impact. They offer differing amounts of support, which means the size metrics can vary. 

Some sports bra brands are sized according to cup and band size just like normal bras - this is usually true of high-impact sports bras.

Other brands (usually those offering low to medium support) don’t have band and cup sizes. Rather the bra sizes range from XS to XL.

Thankfully, most brands do the conversions for you and provide a bra size chart that corresponds to regular bras.

For reference, here's the sizing guide for KFT's Freedom Bra.

KFT bra sizing guide


With my regular bras, I'm typically a 34B and I wear my Freedom Bra in size Medium. The KFT Freedom Bra is ideal for low to medium impact activities.

More information on our sizing here.


How To Check If I’m Wearing The Right Or Wrong Bra Size?

Congratulations! You now know how to measure your bra size at home from the band and cup.

But there’s one more thing left to do. You should check if your current bras are the right bra size.


Check Band Fit

The wrong band sizes can make even the best bras ineffective. 

Featured Product: KFT Medusa Bra in Blue Jay

To ensure comfortable support and a good band size, you should be able to slide one finger underneath the band with about 1 inch of give when you pull the bra away from your rib cage. This ensures the band provides support, not just the straps. 

Also, the band should stay horizontal all the way around your torso. Keep in mind that with every wash, most bras get looser, so you might want to move from the loosest hook to the second (tighter) hook for a better fit, and then ultimately to the tightest hook.


Check Cup Fit

If your boobs are spilling out of the bra, your bra cups are too small.

If, on the other hand, you notice your cups pucker or wrinkle or you have gaping cups, then your bra cups may be too big. 


Check Bridge Fit

The bridge or gore is the piece that connects the two cups. It should sit midway and be flush against your chest wall, not gaping or lifted off the chest.

Also, the underwire should extend all the way to the side under the arm so it supports all of your breast tissue.

The underwire should not be on your boob!

Rather, it should scoop all your breast tissue in. This is especially important in strapless bras that don’t have the additional support from straps.


Check Strap Fit

Featured Product: KFT Medusa Bra in Black

The last thing to check is your bra straps.

Loose or slipping straps can mislead you into thinking your bra is too big. Tight straps can leave uncomfortable grooves on your shoulders or cause neck and shoulder pain. 

Adjusting the straps can make a huge difference in bra fit. Your bra straps should be tight enough to prevent slipping straps but not so tight that they dig into your skin and feel uncomfortable.


Bra Sister Sizes

Another word of advice on this bra size calculator tutorial: It is worth noting that your bra size in one brand may be different from your bra size in another brand.

Something called bra sister sizes can be useful. This means if your usual bra size is 34C but in a particular brand the band feels tight, you should go up a band size and down a cup size, i.e, try a 36B.

On the other hand, if the band feels loose, try a sister size of 32D.


How often should you measure bra size?

Leading lingerie brands recommend getting measured for the right bra every 6-12 months. But there’s no single right answer to this question.

I’d say whenever you go bra shopping, but that can vary widely from person to person.

Or if you’ve recently had weight fluctuations or hormone fluctuations during a pregnancy, then your bust size has likely changed and it’s time to get measured for bra sizes. 


How to ensure the perfect fit in a sports bra?

The overall fit of a sports bra should be snug without any extra room for movement, but it should not be uncomfortably tight.

A well-fitting sports bra does not dig into your skin, restrict breathing, or cut off circulation. When you’re trying on sports bras, it’s not a bad idea to jump around a bit to check the fit. The band should stay in place and you should have freedom of movement while feeling supported in your bust. 


Final Thoughts

Finding the perfect fitting bra can be quite a trial and error. It isn’t just about the complexity of measurement or sizing, but also because our bodies are constantly changing.

But the good news is, once you’ve learned how to measure bra size and zeroed in on the right bra size, if you’re buying the same brand and your current bras are comfortable, you don’t need another fitting. 

You just need to make sure they’re comfortable and supportive!