Free standard UK delivery on orders over £60
Free returns on all orders

2023 bra fitting guide: uncover your perfect size now.

Bra fitting? Yawn, we have heard it all before right? But an astonishing 80% of women are still routinely wearing the wrong bra size. How can this be? 

Well, let us start with a little bit of anatomy. Breast, boobs, knockers, call them what you will, are made of glandular tissue and fat with some strands of connective tissue (known as Cooper’s ligaments) running through. According to the University of Portsmouth Breast Health Research Group,they are held up by nothing more than skin. 

Understanding the anatomy also helps you immediately realise why your breast size changes so readily- whether through hormonal cycles or weight change, the glands and fat content change accordingly. So does your bra size.

When did you last check you bra fitting?

So now you realise, the bra fitting you had 7 years ago, (before 2 kids and a new found passion for bread making) may not still be an accurate reflection of your current breast size.

According to Women’s Health the most common culprits are 34B and 36C: so keep reading especially carefully if you think this is your size!

But who has time to get into the high street to have a bra fitting? Not many of us! The good news is that checking your bra fitting is correct can easily be done at home in a few simple steps. No tape measure involved!

Lady wearing a bra fitting perfectly
A perfectly fitting bra


Find what you consider to be your newest or best fitting bra. Not a sports bra- an everyday underwired one and ideally no so old that all the elastic has perished! Pop it on and find a mirror. Now follow the checks below to see if the size of this bra is actually the best size for you.

The bra pictured here fits perfectly- read on to understand why.


1- Underband

The band is the main source of support in the bra. It is estimated that 80% of the support your bra provides comes from the band. However a band that is too loose is the most common fit error encountered.

There are probably a couple of reasons for this: firstly to avoid ‘back fat’ and maintain a smoother line under clothes. Secondly thanks to the historic ‘add 4 inches’ fitting technique from the 50s which was still employed until recently. In this technique 4 inches were added to the rib measurement to give the band size. This technique is now redundant- it was from a time when there was no elastic in fabric and it literally allowed ‘breathing room’ for a lady in her bra. DO NOT be tempted to adopt this approach in a sports bra- you will be missing out on a huge amount of the support.

The band should sit snug on your ribs. If it rides up at the back it is too loose. If you struggle to do it up on the loosest hooks, it is too tight. Raise your arms up and down, the band should not rise or move on your rib cage.

HINT: If you find you have sore shoulders or indents from your bra straps on them, it is likely that your underband is too loose and you are over tightening the shoulder straps to take the strain.

According to our UK bra size calculator, the underband is too big on this lady
Underband too loose, riding up at the back
UK bra size calculator: bra with the correct fit
Underband correct fitting

2- Cups

Your breasts should be fully enclosed within the cups, there should be no bulging out over the tops creating the classic double boob effect, and also no spillage underneath the arms (this one is not so obvious!) Conversely, there should also be no sagging empty areas in the cups, (unless you are asymmetric, in which case you may have some empty cup space on your smaller side- it is usually best to fit to the larger breast). In a moulded cup bra this will be seen as gaping and your breast not filling the cup fully.

poorly fitting bra- cups are too small
Cups too small, breast spilling into armpit and over the top of cups
UK bra size calculator: women showing a bra where the cups are too big
Cups too big- loose fabric areas over breasts

3- Underwire

The underwire should follow the natural crease of your breast and should not sit directly on breast tissue. They should be flat to your ribcage all the way around and to your armpits. If the underwires pinch, especially under the arm, it is likely the cup size is too small.

4- Center front

The centre front should sit flush against the sternum. If it is sitting away from the breast bone, your cups are too small.

5- Straps

The shoulder straps are mainly there to keep the bra in place, they are not the main source of support. As previously mentioned, if your straps are digging in, you have likely over tightened them to make up for your underband being too loose.

Some bra fitting hints and tips

    • Band rising up at the back or constantly having to pull the back down: Band too loose
    • Shoulders aching by the end of the day: Band too big
    • Inability to breathe easily: Band too tight
    • Straps digging into shoulders: Band too loose
    • Constantly having to ‘tuck’ your breasts back into the cups: Cups too small
    • ‘Double boobing’: Cups too small
    • Gap between center front and breast bone: Cups too small
    • When trying on a bra try to use the middle set of hooks. You will find some bras stretch out over time, or some shrink a little with too much washing
    • Do not try on bras just before your period is due- breasts can be enlarged by a cup size or more at this point in your menstrual cycle.

women wearing a poor fitting bra. Cups are too small
Cups too small- breasts bulging out over top and creating the double boob effect

So now you know how easy it is to check your bra fit at home, no equipment required! It is important for the comfort of your everyday bras but doubly important with your sports bra to ensure they provide the support they are meant to and keep your breasts pain free during exercise.

Once you have your size decided, check out our Power Ratings to figure which bras might work for you and your sport. For example if you love running and are an E cup, you want to be filtering our bras for Power 4 or Power 5 ratings.

If you are still not convinced you have got it right, drop us an email and we can book a virtual fitting to guide you through the steps: