The Ultimate Bra Fit Guide

Discover the most common terms when it comes to bra fit, size and style:

• Band Size: This is the number in your bra size and is based on your underbust measurement, which is where most of your bra’s support comes from.
• Cup Size: This is the letter in your bra size and represents the breast volume in comparison to your brand.
• Underbust Measurement: The measurement around your ribcage directly beneath your breasts. This can help you find the right band size.
• Overbust Measurement: The measurement around the fullest part of your breast, along the nipple line. This is combined with your underbust to calculate cup size.
• Cup Volume: The space inside the cup which changes with your band size. For example, a 16C holds more volume than a 12C even though they both have the same letter.
• Sister Sizing: Bras that share the same cup volume across a variety of different band and cup combinations. For example, a 12D, 14C and 16B are all equivalent, so it can be useful when your exact size isn’t available.
• Bra Fitting: The process of measuring your body to find your correct size. Most Australian women are wearing the wrong size, so a quick bra fitting check can be worth it.
• True Size: The bra size that fits your body right now which may differ from your current bra label.

Most bras are made to last around 6-12 months with regular wear. Common signs it’s time to replace your bra include the band riding up on the tightest hook, the cups gaping or overflowing, the underwire poking through or the straps losing their elasticity. A bra that no longer fits properly isn’t doing its job and you deserve far better support than that!

Hand washing is your bra’s best friend as it can help so keep its shape and support over time. Simply soak in cold water, add gentle lingerie wash and let it soak for 10-15 minutes. Then, gently squeeze the fabric and rinse thoroughly without wringing or twisting. Reshape the cups and leave lying flat or hanging to air dry.

If you’re short on time, you can machine wash with a lingerie bag or delicate cold cycle. Just make sure to avoid using the dryer as this can break down the bra’s elasticity and erode the fabric.

The general rule of thumb is to wash your bras every 2-3 wears. But if you’ve been active, it’s been a hot day or you’ve worked up a sweat, make sure to wash it sooner. Want to extend your wash cycle? Rotate your bras throughout the week, giving each one time to rest and recover its shape between wears.

Store underwire bras stacked cup-inside-cup in a drawer to keep their shape intact and for non-padded bras stack them flat or hang them up. Never store them folded one cup into the other as this can distort the moulded foam and shortens the lifespan of your bra.

Other bra storage tips include avoid cramming them into an overfull drawer where they can get squished, as your collection deserves some breathing room! When travelling, invest in a dedicated bra case or place them in a packing cube to protect their shape in your luggage.

For the most supportive bra, look for full-coverage bras, sports bras and minimiser bras. For everyday wear an underwire bra in a fuller cup style can provide great support and comfort for daily wear. While a high-impact sports bra is a must-have for support when exercising. If you have a larger bust, look for bras with wide straps, broader back bank, side slings or reinforced cups for life and stability.

The main difference between wire and wireless brans is the wire itself. A wire bra features a thin wire sewn into the base of each cup to define, lift and distribute weight evenly for added structure and support. This makes them an ideal option for larger bust sizes.

Alternatively, a wireless bra (or wire-free bra) relies on stretchy fabrics, panels and clever construction for a softer and more flexible fit. This is a popular choice for comfort, loungewear and smaller cup sizes where less structure is required.

A good rule of thumb is 3-5 everyday bras in regular rotation if you’re doing your laundry weekly. This allows each bra enough time to rest between wears as elastic needs 24-48 hours to recover its stretch and can help to extend the life of your collection. But beyond your everyday bras, it’s helpful to invest in different styles, like a strapless bra for off-the-shoulder looks, a sports bra for workouts or a t-shirt bra for fitted tops.

Bra sizes combine two measurements: a number (the band size) and a latter (the cup size). The number is your underbust measurement, which is the circumference around your ribcage, just below your breasts. While the letter is your cup volume, which is the difference between your underbust and your fullest bust measurement. So, for example, a 12C means a band that fits a 12 (approximately 70–75cm underbust) with a C cup.

The number is your band size, which corresponds to your underbust circumference. In Australia, band sizes typically run in even numbers like 8, 10, 12, 14, 16, 18 and beyond. While the letter is your cup size, which reflects the volume of your breast relative to your band. It starts at AA (smallest) and goes up through A, B, C, D, DD (or E), F, G, and further. However, cup size is not fixed, and it can change with band size. For example, a 12D and a 14D can hold different volumes. This is commonly called "sister sizing" and is worth understanding if you're between sizes or struggling to find your perfect fit.

If your calculated bra size feels “off,” it is most likely because different women’s bra brands may fit slightly differently on your body. Many people also need:

• Sister sizes, perfect for when the cup fits but the band doesn’t
• Go down a band → up a cup (e.g. 34C → 32D)
• Go up a band → down a cup (e.g. 34C → 36B)
• Adjustments depending on how tight you like the bra band to be

• ❌ Pulling tape too tight under bust → band too small
• ❌ Letting tape dip in the back → incorrect band
• ❌ Measuring over padded bras → inflated bust size
• ❌ Standing hunched or pushing chest out → inaccurate result
• ❌ Using only one measurement (you always need both)