You've probably heard the statistic before: studies suggest that up to 80% of women wear the wrong bra size. What's more surprising is that many women don't realise their bra doesn't fit correctly. Over time, we become accustomed to minor discomforts and don't recognise them as signs of an ill-fitting bra. Learning to identify these warning signs is the first step toward finding a bra that truly supports and flatters your figure.
A well-fitting bra should feel comfortable from the moment you put it on. It shouldn't require constant adjustment, leave marks on your skin, or cause any pain. If you've been experiencing any of the following issues, it's time to reassess your bra size using our free Australian bra size calculator.
The Band Rides Up Your Back
One of the most common signs of a wrong bra size is a band that rides up at the back. When you look at yourself from the side in a mirror, your bra band should sit horizontally across your back, running parallel to the floor. If it's higher at the back than at the front, your band is too loose.
This issue is particularly problematic because the band provides approximately 80% of your bra's support. When the band rides up, your straps have to compensate by working overtime, leading to shoulder pain and groove marks. The cups may also sit too low, failing to provide adequate lift and separation.
The solution is usually to go down a band size. Remember that when you decrease band size, you should go up a cup size to maintain the same cup volume—this is the sister size principle in action.
Your Straps Keep Falling Down
While straps can be adjusted for different torso lengths and shoulder positions, constantly slipping straps often indicate a deeper fit issue. Straps that won't stay put might mean your band is too large, causing the entire bra to shift around rather than staying anchored in place.
Before assuming you need a smaller band, consider your shoulder shape. Some women have sloping shoulders that make strap slippage more likely regardless of fit. In these cases, styles with straps set closer to the centre or racerback options might provide a better solution.
However, if your straps slip and you also notice other signs of poor fit, a smaller band size is likely the answer. A properly fitted band keeps everything in place, allowing the straps to simply guide the cups rather than doing heavy lifting.
You See the Dreaded Quad Boob
Quad boob, also known as double boob, occurs when breast tissue spills over the top of your bra cups, creating a visible ridge under clothing. This is almost always a sign that your cups are too small—your breasts need more space than the bra is providing.
Many women resist going up in cup size because they underestimate their actual cup size. Larger cup sizes are more common than many people realise, and there's no reason to squeeze into a cup that can't contain all your breast tissue properly.
When your cups fit correctly, all breast tissue should sit comfortably within the cup with no spillage at the top or sides. The top edge of the cup should lay flat against your skin without cutting in.
Gaps or Wrinkles in the Cups
The opposite problem is equally common: cups that gap or wrinkle because they're too large for your breast tissue. This is particularly visible in moulded or padded bras, where the cup maintains its shape regardless of what's filling it.
Gaping cups suggest you should try a smaller cup size. However, before making that change, ensure you're putting your bra on correctly. The scoop and swoop method—leaning forward, placing your breasts in the cups, then using your hand to sweep tissue from under your arms into the cups—ensures all your breast tissue is properly positioned. Sometimes what looks like gaping is actually tissue that hasn't been properly scooped into place.
Cup shape can also cause gaping. If you have shallow or wide-set breasts, a deep, narrow cup might gap even if the volume is correct. Consider trying different cup shapes rather than just changing sizes.
The Centre Gore Doesn't Tack
The centre gore is the piece of fabric or wire that connects the two cups at the front of your bra. In a properly fitting bra, this gore should sit flat against your sternum, with the fabric touching your skin at all points. This is called "tacking."
If your centre gore lifts away from your body, your cups are likely too small. There isn't enough room for your breast tissue, so it pushes the gore forward. This is one of the most reliable indicators that you need a larger cup size.
In some cases, a non-tacking gore can relate to breast shape rather than size. Women with close-set breasts may struggle to find a gore that tacks properly because there simply isn't enough space between their breasts. Plunge bras with very low gores can help in these situations.
Underwires Poke or Sit on Breast Tissue
Underwires should encircle your breast tissue completely, sitting in your inframammary fold (the crease where your breast meets your torso) and extending around to the side of your chest wall. If your underwires poke into your breast tissue, sit on top of it, or dig into your armpits, something is wrong.
Wires that dig into the front of your breast usually indicate cups that are too small—your breast tissue is being compressed and pushed into the wire. The solution is a larger cup size that properly contains all your tissue.
Wires that poke under your arms might mean the cups are too wide for your breast shape, or that the wire is extending too far back. Different bra styles have different wire widths, so experimenting with various brands might help.
You Have Red Marks at the End of the Day
Some light marking from your bra band and straps is normal, similar to the marks left by socks around your ankles. However, deep, red, or painful marks indicate that something is too tight.
Deep groove marks on your shoulders suggest your straps are doing too much work, likely because your band is too loose. Addressing the band size should reduce the pressure on your straps.
Marks around your ribcage from the band might indicate a band that's too small, but can also result from wearing your bra on the tightest hook setting before the band has stretched out. New bras should be worn on the loosest hook, moving to tighter settings as the elastic relaxes over time.
Time to Recalculate Your Size
If you've recognised any of these signs in your current bras, it's time to remeasure and recalculate your size. Our Australian bra size calculator makes this process quick and easy—simply enter your underbust and bust measurements to discover your correct size.
Remember that your bra size isn't static. Weight changes, hormonal fluctuations, aging, and other life events can all affect your measurements. Regular size checks—every six to twelve months—help ensure you're always wearing a size that truly fits.
Once you know your correct size, you'll immediately notice the difference a well-fitting bra makes. Better support, improved posture, enhanced comfort, and a more flattering silhouette under clothing are all within reach when you wear the right size.