Bra Size Calculator

Discover your bra size with our simple bra size calculator. Supports Australian, international, and sister sizing options.

How To Measure

CM

INCH

Underbust Measurement

Measure around your ribcage, directly under your bust. Keep the tape snug but not tight.

75cm

60cm 130cm

Bust Measurement

Measure around the fullest part of your bust. Keep the tape parallel to the ground.

100cm

76cm 170cm

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Australian Size

Sister Sizes

Tighter Band

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Looser Band

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International Sizes

UK

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US

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EU

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FR

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IT

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Shop Bras Get Fitted

How To Measure

To find your bra size, measure your underbust and overbust with
a soft tape and a mirror. Follow these steps for accurate results.

1. Underbust

Wrap the tape snugly around your ribcage, just below your bust, to determine your band size. Keep it level and firm but not tight.

2. Overbust

Measure around the fullest part of your bust, keeping the tape relaxed and level. This is generally in line with your nipple.

3. Calculate

Input your underbust & overbust measurements into the bra calculator for your Australian bra size, conversions, and sister sizes.

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Need A Hand?

Get A Bra Fitting in Melbourne!

Struggling to find your perfect bra size? Visit our Melbourne lingerie store for a free bra fitting and personalised expert advice. With over 40 years of experience, we understand the challenge of discovering a bra that fits just right which drives our passion for helping women feel comfortable and confident every day.

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Sister Sizing Explained

Sister sizes are bra sizes that share the same cup volume but differ in band size, offering a way to tweak the fit without changing how much space the cups provide. For example, if a 12D feels too tight around your ribcage, its sister size, 14C, has a larger band but the same cup capacity, potentially giving you a more relaxed fit. Conversely, if the band on a 12D is too loose, trying a 10DD might snug things up while keeping the cups consistent.

The concept works because as the band size changes, the cup size adjusts inversely - one size up in the band means one size down in the cup, and vice versa. Our bra size calculator includes sister size suggestions alongside your primary result, making it easy to explore these options. This is particularly helpful when shopping brands with limited size ranges or when your body falls between standard sizes.

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A Note on Bra Size Calculators

Even with precise measurements and a reliable bra size calculator, you might notice that your calculated size doesn’t always fit perfectly - and there’s a good reason for that. Bra sizing can vary significantly between brands, styles, and even colours within the same brand, making it tricky to rely solely on a calculator.

For instance, one company’s 12C might fit snugly, while another’s feels too loose due to differences in how they cut their patterns, the stretchiness of their fabrics, or the shape of their cups. Even small details, like the width of the straps or the placement of the underwire, can affect fit. This is why lingerie experts recommend getting a professional bra fitting in addition to using a bra calculator. A fitting specialist can assess how a bra sits on your body, check for signs of a poor fit (like straps slipping or cups overflowing), and suggest adjustments tailored to your shape - something no calculator can fully replicate.

Your Questions, Answered!

Australian Bra Size Calculator FAQ's

Here are our most common questions to assist you in finding your perfect fit.

How do I measure my bra size accurately?

To measure your bra size accurately at home and get the best results from a bra size calculator, you’ll need to take two key measurements: your underbust and overbust, using a soft, flexible measuring tape. Start by wrapping the tape snugly around your ribcage, just below your bust, to find your underbust size - this determines your band size, like 10, 12, 14 etc in Australian sizing. Then, measure around the fullest part of your bust for your overbust, keeping the tape level and relaxed, not tight, to calculate your cup size (e.g., A, B, C, etc). For the most precise outcome go braless, stand naturally, and use a mirror to ensure the tape stays even all around your body. Our step-by-step guide and calculator make it easy to input these numbers and find your perfect bra size, whether you’re measuring in centimeters or inches.

How often should I check my bra size?

You should check your bra size every six months or whenever you experience significant weight shifts, pregnancy, or lifestyle changes, as these can alter your measurements and affect how your bras fit. Experts suggest this frequency because even small fluctuations - say, a few kilos -can change your underbust or overbust enough to shift you from a 12C to a 14B, and using an accurate bra size calculator regularly keeps your wardrobe updated. Life events like starting a fitness routine or hormonal changes can also impact your size, so re-measuring ensures you’re always wearing a bra that supports you properly. With our easy-to-use calculator, you can quickly recheck your Australian bra size and its international equivalents at home anytime.

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