How To Measure Bust Size

A bra fitting guide, or how to measure bust size. It should be simple right? Wrong! If you want to read the traditional method of doing this, click on fitting a bra. However as I explain on that page, that process is deeply flawed.

How to measure bust sizes

To be able to provide a better advice on how to measure bust size I have researched many reference books, waded through numerous clothes catalogues and measuring guides from shops, trawled the internet, read blogs and was measured in four different shops.

Some information I found was good, a lot out of date and much contradictory – but I feel that I can now provide a good guide as to how to measure a bra for a woman with a big bust and it was a surprise to me.

If you were actually after information on cup measurements? Have a quick peek at the page on bra sizes.

So how To Measure Bust Size
For a Bigger Bust?

A while back I went to Rigby & Peller, possibly the most famous British brassiere supplier; with a Royal warrant of Appointment as Corsetieres to H.M. Queen Elizabeth II since 1960. The fitter there was absolute quality and she did not use a tape measure. So what did she do?

She simply made a reasoned judgement. In the UK that is what many of the big stores do now. Bravissimo even baldly states ‘you won’t find our fitters using a tape measure’.

So do what the more enlightened brassiere fitting specialists do. You use your experience and common sense. You conjecture, suppose, imagine, surmise, assume, reckon and estimate. Simply put, you guess.

Common sense is seeing things as they are; and doing things as they ought to be.   

Harriet Beecher Stowe

But it is not an ignorant or clueless guess. You use your common sense and experience. Take a look at the page on the best bra for large cup sizes, which explains important issues for a good fit.

Let's face it, how long have you been wearing a bra? and who knows your boobs better than you? Harriet Beecher Stowe was clearly talking about bust measurement.

Of course it is better with an experienced fitter or a second pair of eyes but you can make a very good go at this yourself, without the fuss or embarrassment. It is a two step process;

(A) assessing the size needed

(B) buying some bras on the internet or go shopping, to test your bust measurement

          Bust Measurement
(A) Assessing What Is Needed

How to measure bust size

  1. The band
  2. The cups

First, stand in front of a large mirror in one of your badly fitting bras, taking a note of the stated brassiere size. The best place to start on how to measure bust size is the band, or under-band.

(1) The band:

Band too loose? How do you tell. Firstly swivel, look in a mirror and see if it has ridden up at the back. This is a classic means of determining that it is too loose. When proper fitters are looking how to measure a bra they will pull from behind and guage the amount of give.

If you can get your hand up you back, try it, but if not pull the front. You are only meant to be able to get one finger under, so if you can really pull it away you know it is too loose.

Another sign is straps digging into your shoulders. Why? Because the band is loose and not tight enough to do it's job efficiently. Equally if the centre piece is not flush on your breast bone, it is often a good indication of looseness.

Band too tight? Do the opposite, try a bigger band size, but be very careful. Classic signs are the under-wiring or bands digging in, a rash or soreness when the brassiere is removed or red marks or indentations on the flesh. Just remember, bands are meant to be taut, strapless bra bands almost painfully tight. 80% of the support comes from the band and it needs to be taut.

(2) The Cups:

The second issue in how to measure bust size is obviously the cups. You breasts should not bulge over the top, the sides or underneath; a common enough issue for women with big boobs but indicative that you probably need a bigger cup size.

Conversely if the top of the cup is loose, baggy, or if there is wrinkling then it is probably too big. Perhaps you have lost weight or the bra has stretched. However it could be your breast shape.

To remind yourself what the key factors are for a prefect fit, take an detour to the page best bra. Oh and by all means measure yourself by the traditional method too, it is still a useful indication.

           Bust Measurement
(B) Try On A Variety Of New Bras

Well you don't buy a car without getting in and trying it out. So you need to try some different size bras. You now know from the above testing if the problem is the band is too tight or too loose and similarly for the cups.

As above, test the band first then the cups. Even if it appears to be both, concentrate on the band first. As any phone or web techie will tell you - band width matters!

(1) The Band:

Remember, if you do go up a band measurement you might need to reduce a cup size and conversely if you reduce the band size for a tighter fit you will go up a cup size.

Often times, if you have not gone through this whole 'how to measure bust size' process for a while, you can actually move two band sizes, for example. 36E to 32G. That was actually what happened to me a few years back.

As bras age they lose their shape and loosen plus many women find they only ever seem to get bigger breasts. So it is no surprise that the majority of shop fittings report women wearing bras that are too loose.

(2) The Cups:

Width may be where you start the process but cup sizing is the area where your own boob shape and different styles of bra make a big difference to you personally. It is the key to how to measure bust size for you as an individual.

You may find yourself spilling out of the first new bra you try in a 32H for example. This may be because you are fuller in the upper breast. But do not simply mentally strike out an H cup. First try a different style bra, an H cup balconette bra might fit perfectly, for example, whereas a 'full cup' style might not.

Different boobs suit different bra styles it is primarily to do with your breast shape. Even the positioning of the seams on the cup, can make a world of difference and every issue is literally bigger, for a large breasted woman.

So actually it is the cup size and bra style that you actually need to devote the time to when experimenting - the band sizing is simple in contrast. All the above is a bit long winded but when you learn how to measure bust size, you do it because you want to guarantee a perfect fit.

A Fabulous Online Bra Size Calculator

There is one online bra size calculator that deserves a mention, the one at the Canadian Butterfly Collection website. Try it out, getting an accurate bust measurement is important and this is about as good as it gets and those Canadian folks deserve credit for creating such an excellent tool.

I am not going to recommend any style or manufacturer, we are all big girls and can make our own minds up; anyway, this page is more about how to measure a bra. By the way, all the above pictures are from bras listed on Amazon and if you want to see more detail, simply click the photo. It's entirely your choice!

  • To return to the top of the page, click how to measure bust
  • For the main page on bra related topics, including a look at different types of bra and issues for the big busted, head to the main page big bras
  • Otherwise skoot back to the Home page for more general discussion on clothes for big breasts.


Did you like this page, did you learn something, maybe it reinforced you own views? I want to give as much (hopefully helpful) advice to the busty sisterhood as I can.

Please remember, we are all different. You may like to wear certain clothes and styles which I am suggesting that you should not. That is your absolute right. Do what makes you feel good. This site undeniably goes for the more modest approach because I feel all busty ladies already know how to be more racy if they wish.

It would really help me improve the site profile if you would click the Facebook 'Like' button. Pretty please! Susan

Please share this page

Women's Two Biggest Bra Worries:

Back Fat - a real worry for many women

(1) Back fat

(2) The embarrassment of a big cup size

The good news is that sometimes back fat can be caused by a badly fitting bra. When you get the correct bust measurement that problem can be much reduced, or disappear completely.

As for embarrassment. You will get over it. What really matters is looking good and if that means a bigger cup measurement, so be it. Most people will never know your dimensions anyway.

It is therefore crucial for any busty woman to know how to measure bust size.



The Unbridled Joy of
a Great Big Cup

The unbridled joy of big cups

You think he is happy winning the cup? You wait until you work out how to measure a bra and then get the perfect cup fit. One fleeting moment of unbridled pleasure like him, or comfort and support on a daily basis.

Plus you get to look good. I mean, it seems lost on him and all the men cheering him, that he actually has his thighs wrapped around another man's head!


The Perfect Cup?

The perfect cup!

Sorry, just another musing from a tea obsessed Brit!



Bust Measurement -
When the research got weird

As an aside, during my research I even sat through 80 different youtube videos on how to measure bust size. The strangest ones have got to be by a middle aged man from Phoenix, USA doing a fitting.

He hooks the back up, adjusted the straps and stood there pointing things out on his live model.

I am sure he had been in the trade for a while and knew how to measure a brassiere and much besides, but it was very odd; and when he got prosthetic breasts out it moved into the realms of surreal.

As for when he said he said he fitted 13-14 year old girls....



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If you are particularly interested in fashion; clothes for big breasts; or simply have a top heavy friend that you know might appreciate the site; please help me reach others by tweeting or sharing through any social media you use.

Nothing helps a site like this more than 'normal' people (not clever marketeers) simply sharing a page or two.

Susan