How To Measure Your Bra Size

Need to know how to measure your bra size correctly? Wondering what bra size you really need? De-stress your breasts with Knixteen’s handy bra sizing guide.

If there’s one thing out there that’s almost as annoying as your period, it’s finding your bras. When I graduated to a bra that looked less like a cotton sports bra and more like a “grown-up” bra, I remember having no idea what size to get. I was used to the small/medium/large bra sizing so understanding band and cup sizing was the equivalent of trying to learn Japanese.

I’ve been measured for my bra size by various store clerks numerous times and every single time they give me a different size bra. The problem with this is most of the time I was measured with a padded bra on that made my boobs seem bigger than they were, or a sports bra that constricted my boobs and made them seem smaller. I was also almost always measured with a shirt on, which throws off the bra’s band measurement. Naturally, I didn’t know any of these things could alter my actual bra size, so I listened to the store clerk and bought the wrong bra sizes for years.

It wasn’t until literally a month ago that I learned my correct bra size. To put this into perspective, I’m 24 years old. I should know my bra size! Don’t worry, I won’t let you make the same mistake. If you’re a teen and you’re looking to buy your first bra, you’ve come to the right place. I’m going to save you from years of discomfort and wasted money on the wrong bras, and teach you how to correctly measure your bra size with Knixteen’s guide to bra sizing. First, I’m going to go over some of the telltale signs that indicate you’re currently wearing the wrong bra size. Let’s get into it!

How to tell if you’re wearing the wrong bra size

If you’re already wearing bras or just purchased your first bra, there are a few ways to tell if the bra is too small or too big for you.

1. The straps dig into your shoulders

This is what was always happening to me. My straps always dug into my shoulders and I assumed it was just the way my shoulders were and this was a necessary evil of bras - wrong! If your straps dig into your shoulders or leave red marks, this means your boobs are relying on the straps for support when they should be relying on the band. Odds are, you need to be wearing a smaller band size.

2. Everything is jiggling

This should seem obvious, but sometimes people just assume that a frilly, lace bra equals minimal support but that’s just not true. If you’re wearing the right size bra, even one with minimal padding or wires should hold your boobs in with minimal movement.

You might be wearing the wrong cup size or band size, or it could be a mixture of both. If this is happening to you, your bra is too big and you need to size down to find your correct bra measurement.

3. Your boobs spill out of the cups

We all want a little boost for the girls, I get it! However, a properly measured padded bra will give your boobs that extra perk without a nip slip. If your boob has a little hump over your cup, the cups are too small and you need to go up a bra size. Getting a smaller bra does not equal better cleavage - it just looks like you have 4 boobs instead of 2, so get a bigger bra!

4. The band is squeezing your back

Similar to the strap issue, if your band is digging into your back or leaving red marks when you take it off, you’ve probably had your bra measured too small. Having a band that’s too small also creates and awkward hump where your bra is that becomes visible under tight shirts, which is zero fun! If this is happening to you, go up a bra size.

5. You’re adjusting your bra throughout the day

Contrary to popular belief, the right bra should be comfortable. If you’ve measured your bra size correctly, it should feel like this barely-there article of clothing. Wearing the right bra size can make a huge difference in terms of comfort.

If you find you’re constantly adjusting your straps, or changing the hook your band is on, you’re wearing the wrong bra size. Once you put on your bra you shouldn’t have to touch it, so if you’re constantly fidgeting you need to be wearing a different bra size.

How to measure your bra size

Measuring your bra size for the first time can seem confusing, but it’s worth measuring yourself to know your exact size. I find doing this at home is more effective than getting a store clerk to do it for you.

Ideally, you should do this in private without any clothing on, as it will give you the most accurate measurement. Need someone else to help measure your bra size but don’t feel comfortable being without your bra and shirt? Keep your bra off and wear a thin t-shirt overtop to accurately determine your bra size.

If you read any of those above signs and thought hmm, that happens to me all the time, you need a new bra! Here are the steps on how to properly measure your bra size.

1. Get a measuring tape

Before finding your bra size, you need one of those fabric measuring tapes, like this one, so you can wrap it around your body. Most fabric stores have one and they’re super cheap, so it’s worth going out and getting one!

2. Measure your bra’s band size

To correctly measure your bra’s band size, take the measuring tape and wrap it around your rib cage, right underneath your boobs. Take the band measurement in inches, not centimetres (it saves you the conversion).

Once you know the measurement in inches, take the number and add two inches to get your band size. For instance, my underband measures at 30 inches, so I take that number and add two, meaning my band size is 32!

Most bras start with a size 30 band. If your underband is measuring anything under a 28, size up to a 30 band or stick with small/medium/large sizing in the meantime.

3. Measure your bra’s cup size

To accurately measure your bra’s cup size, you want to wrap the measuring tape around the fullest part of your breast, which is usually right where your nipple is. Once again, take this measurement in inches. When you have the measurement in inches, you want to use your original underband measurement and calculate the difference between your underband and cup.

To give you an example, the fullest part of my breast measures at 33 inches. My original underband measurement was 30 inches, so the difference is 3 inches. For every inch of difference, it’s one cup size. If there was a one inch difference, I’d be an A cup, a B cup for two inches, a C cup for three inches, etc. Since there’s a three inch difference, I’m a C cup.

4. Put it all together

Based on these steps, my bra size is a 32C! If you follow these steps and find you’re wearing the correct bra size but you’re still experiencing discomfort with your bra, you probably need to switch up the type of bra you’re buying or the bra store you’re shopping at.

Luckily for you, we’re launching five bras this year, with the first two bras being released in September. Follow us on Instagram to get the latest updates on the official launch date.

Sister sizing your bra size

If you’ve never heard of ‘sister sizes,’ it’s essentially a bra size that’s similar in fit to your actual bra size. To figure it out, take your band size and go up one size and take your cup size and go down one size.

For instance, since my bra size is a 32C, my sister size would be a 34B. While is won’t be as supportive as the 32C, it’ll still fit properly. Getting your sister size is a good option if your usual bra size is sold out.

Hopefully after reading this you’ve become a bra sizing expert, and you can confidently find the correct bra size for you! For more information on our upcoming bra launch, visit the Bra Boss page of our website.

Get our latests posts straight to your inbox.