18G
18G Bra Size Collection
Your Guide to the Perfect 18G Fit
If you're shopping for bra sizes that actually get you, you're in the right place. The 18G bra size is designed for bodies that need both generous cup volume and secure band size support. At The Foundation, we're all about making that search easier, more empowering, and honestly, more enjoyable. Our expert bra-fitting service and in-store options are available to make finding the right fit as stress-free as possible.
What Does 18G Actually Mean?
In Australian sizing, size 18G represents a band size of 18 (underbust measurement around 100 cm, with 40 inches provided as a reference only) paired with a G cup—which means a fuller bust volume. It's a size that offers both a supportive band and a generous cup for balance, comfort and shape.
Breakdown:
- Band size 18 (AU): Underbust around 98–102 cm
- Cup size G (AU): A 20 cm difference between underbust and overbust
This size is ideal for fuller-busted individuals who need structure without sacrificing comfort. If that sounds like you, keep reading.
International Size Conversions
| Region | Size Equivalent |
|---|---|
| Australia (AU) | 18G |
| UK | 40F |
| US | 40I |
| EU | 90G |
| France (FR) | 105G |
Always double-check the sizing label when shopping international brands.
How to Measure: A Quick Fitting Guide
You don’t need a professional fitting to get started (though we’d love to help in-store or via our virtual bra fitting service!). Grab a tape measure and follow these steps:
Step 1: Measure Your Band Size
- Wrap the tape measure firmly under your bust (where your bra band usually sits).
- Make sure it’s snug and level all the way around.
- Round to the nearest even number in centimetres. That’s your band size.
Step 2: Measure Your Bust Size
- Measure around the fullest part of your bust.
- Keep the tape comfortably snug (not tight).
- Subtract your band measurement from this number. The difference in centimetres determines your cup size.
| Difference (cm) | Cup Size |
|---|---|
| 20 | G |
For example: If your underbust is 100 cm and your overbust is 120 cm, you’re an 18G bra size.
Sister Sizes for 18G
Sister sizes share the same cup volume but vary in band size. If your 18G bra feels too tight or loose in the band, try these:
These sizes are useful if you're exploring our DD to G Cup bras range or if you're guided by a D-K cup bra-fitter in-store.
Best Bra Styles for 18G
When it comes to supportive style without bulk, our 18G range delivers:
- Underwire bras for structure and lift
- Wireless bras: Flexibility + lift without the dig
- Lightly padded bras: Smooth shape without exaggeration
- Seamless styles and seamfree contour bras: Everyday ease, perfect under tees
- Side support bras and side sling options: Keep everything front and centre
- Full coverage bras and full cup styles: Ideal for maximum comfort
- Sports bras in Low, Medium and High Impact support levels
- Maternity and nursing bras that support evolving shapes
- Adjustable straps, wide straps, and hook eye and closure backs for optimal fit
Whether you're after an Everyday Bra, a lacy bra for special occasions, or curvy bras made for comfort, we've got you.
Featured Brands in 18G at The Foundation
We carry a thoughtful curation of lingerie brands that specialise in fuller bust lingerie, including:
These brands bring you supportive bras that blend premium support with beautiful design. Our Full Cup range is carefully selected to support bust projection with quality power mesh fabric, delicate lace, and thoughtful design features like contrast colour lining.
Need Help Finding Your Fit?
We’re here to help—online, by phone, or in-store. Whether you're new to your bust measurement, looking for a bra fitting, or exploring plus-size bra styles, our expert fitters are always ready.
Check our Size Guide Get in Touch Visit a Store Sign up to receive special offers and the latest news.
Ready to Feel the Difference?
Your perfect fit starts here. Shop our curated 18G collection—featuring regularly updated stock availability—so you never miss out on the styles that suit you best and discover bras that support, flatter and empower. Whether you're shopping for a staple or something special, we've got 334 items to explore.
FAQs About 18G Bras
What does 18G mean in bras?
It refers to a band size 18 (approx. 100 cm underbust) and a G cup, which offers generous bust coverage and support.
Is 18G the same in every country?
No. For example, 18G in AU is a 40F in the UK and a 40I in the US. Always check the size chart before buying internationally.
What if 18G feels too tight or loose?
Try sister sizes: 16H for a snugger band or 20F for a more relaxed fit. Sister sizes maintain the same cup volume but adjust the band size, offering more flexibility in achieving a personalised and comfortable fit. Visit us for an expert bra-fitting service or try our Bra Finder online.
Are there wireless options in 18G?
Absolutely! Brands like Elomi and Anita do beautiful wireless bras in this size that still give you shape and support.
Can I return my bra if it doesn’t fit?
Yes—just make sure it meets our returns policy. And don't forget to use a laundry bag to care for your pieces properly.