Why Taking Measurements Doesn’t Work for D+ Cups

Why can’t bra sizes be as simple as taking a few measurements? Surely bras are just like any other clothing item and the sizes just line up with different measurements?

If you’ve got a fuller bust, you already know the struggle: finding a bra that fits is next-level hard—and relying on measurements alone often makes it worse.

So what’s the deal? Why is the whole “measure-underbust-and-overbust” thing so wrong for women over a D cup?

Let’s break it down.

Traditional Bra Size Charts Were Never Designed for D+ Cups

Most bra sizing systems (especially traditional or department store ones) were built around small cup sizes—think C or D at most. So when you start applying the same formulas to E, F, G or H cups, the math just doesn’t add up.

The two measurements everyone wants to know when you’re bra shopping are your underbust measurement, and overbust measurement. Your underbust measurement is taken around your ribcage, directly underneath the roots of your breasts. Your overbust measurement is taken around the fullest part of your bust (for most people this is over the nipple), usually without a bra on.

Underbust + Overbust = Bra Size… Right?

The idea is that your underbust measurement determines your band size, and the relationship between your underbust measurement and your overbust measurement determines your cup size. 

For smaller cup sizes, this is pretty straightforward. If your overbust is one inch bigger than your underbust, congrats, you’re an A cup. If your overbust is two inches bigger than your underbust, you’re a B cup, etc.

You might already see the issue here.

These three ladies have the exact same underbust and overbust measurements:

But they’re clearly not the same bra size!

There are so many crucial things measurements can’t tell us, like:

• Are you full on top or full on bottom?
  
  

• Do you have wide-set or close-set breasts?
  
  

• Is your tissue soft or firm?
  
  

• Do you need more depth or more width?
  
  

If all of that wasn’t enough, it turns out that measuring yourself can actually be a bit tricky, and human error is very, very common. So the numbers you end up with might not even be entirely accurate!

So are measurements useless?

Not entirely!

Your underbust measurement is still helpful for us to have when we’re helping you find your bra size. 

Underbust is a bit easier to measure, without the whole soft boobs factor complicating things. Underbust measurements are a great tool to help indicate your band size!

What Works Better Than Measurements? 

In short, bra fitters!

Calculators and measurements will never be able to give you the accurate, detailed advice that a human, expert bra fitter can. Going into a lingerie boutique to get professionally fitted in person is hands-down the best way to find your bra size.

Don’t live near a suitable boutique?

If you’re after quick size advice, instead of a calculator, we have a Fit Quiz to help point you in the right direction. This quiz was designed by bra fitters - we ask the questions we’d want to know in any fitting, no tape measure required.

Even better, our actual bra fitters from our showrooms spend their mornings online, helping out busty ladies all over the world with the same kind of personalised feedback you’d get if you came to get fitted in store.

Submit an E-Fitting to get in touch - we just need that underbust measurement, then you can toss aside the tape measure. Our fitters fit by eye, both in the showroom and online, which means they can pretty accurately determine your true bra size just by looking at you in any bra - call it a superpower! 

That means the single best thing you can do in your E-Fitting to receive accurate size advice is to include a couple of quick pics of yourself in your best-fitting bra. Your fitter will take it from there, emailing you back with any follow-up questions, all of her thoughts, and recommendations for which bras will best suit you.

You’re Not Hard to Fit—You’ve Just Been Mismeasured

If you’ve been told to "just measure yourself" and now you’re stuck in a pile of ill-fitting bras, it’s not your fault.

The truth is: bras are complicated. Big boobs are nuanced. And tape measures are not magic.

So let’s skip the bad math and focus on what actually works: learning what support feels like, and getting in touch with experts who get it.

Ready to Find a Bra That Actually Fits?

• Submit a free E-Fitting
• Book a video call with a fitter
• Take our quick Fit Quiz