18D Bra Size – Find Your Perfect Fit
Understanding the 18D Bra Size
Shopping for the right bra starts with understanding what your size means. An 18D bra size in Australian sizing combines a band size of 18 (AU/NZ) with a D cup. This means your underbust (or back size) measures approximately 98–102 cm, and your bust measurement is around 112–114 cm. A D cup indicates a 4-inch (10 cm) difference between your band and bust size—this is how cup size is calculated.
International Bra Size Conversion Table
Need to match your Australian size with international sizing? Here's a handy conversion table:
| Region | Equivalent Size |
|---|---|
| Australia/NZ Size | 18D |
| UK / US / Canada Size | 40D |
| European Size (EU) | 90D |
| French Size (FR) | 105D |
How to Measure Your Bra Size
Use a tape measure and follow these bra fitting guidelines:
- Step 1: Measure your band size
Wrap the tape snugly under your bust and round to the nearest even number. This gives you your band size. - Step 2: Measure your bust
Measure the fullest part of your bust to get your bust measurement. - Step 3: Calculate your cup size
Subtract the band size from your bust size. Each inch difference equals one cup size. For example, a 4-inch difference equals a D cup.
Explore Sister Sizes
If your bra doesn't feel quite right, try sister sizes. These offer a similar band and cup size balance with slight variations in fit:
Top Bra Styles for 18D
At The Foundation, we specialise in supportive, stylish bras for every need:
- Lightly padded bras – Provide subtle shaping without bulk
- Wireless bras – Ideal for all-day stretchy support
- Seamless bras – Perfect under clingy or fitted clothing
- Plunge bras and 3D Plunge Contour styles – Flattering for deep necklines
- Full Cup Control Bras – Designed for fuller busts needing superior coverage and control
- Strapless bras – Reliable support without straps
- Soft cup bras – Flexible and comfortable support
- Sports bras – Including the Active D+ Classic and Ultimate Run Bra for high-impact support
- Maternity and nursing bras – Supportive options designed for comfort and ease of feeding
Curated Brands Available in 18D
Our fuller bust lingerie range includes trusted lingerie brands known for comfort, style, and quality:
Need help choosing? Our expert bra-fitting service is available both in-store and via virtual bra fitting services. Our friendly team is trained to fit D–K cups and beyond, ensuring you leave feeling confident and supported.
Quick buy and FREE SHIPPING on orders over $150, plus exceptional customer service, make shopping easy. Start shopping the 18D bra collection now.
FAQs
What does 18D mean in bra sizes?
18 is your band (back) size and D is your cup size. It’s based on Australian sizing.
How do I know if 18D is my correct size?
Follow our bra sizing guide or book an in-store bra fitting.
What if 18D feels uncomfortable?
Try sister sizes like 16DD or 20C depending on whether the issue is with the cup size or band size.
What styles work best for D cup sizes?
Full cup, soft cup bras, and plunge bras offer support and shape without compromise.
Can I return my bra if it doesn’t fit?
Yes – as long as it's unworn and has tags attached. Read our full Returns Policy.