AU Size To US Size Conversion Guide

Why does an AU 8 in women’s clothing equal a US 4 but an AU 8 shoe often equals a US 8?

Key Takeaways

• For women’s clothing, converting the AU size to US size usually means subtracting four. For example, AU 8 commonly corresponds to US 4, although shoppers should still compare the brand’s measurements. 
• Men’s clothing doesn’t have one fixed AU-to-US conversion. Compare chest, waist, and inseam measurements instead.
• Women’s AU and US shoe sizes are generally the same, but men’s sizes differ by one size. 
• For bra bands, add 22 when converting an AU bra size to US sizing. For example, an AU 12D converts to a US 34D, although cup letters begin to differ above D.
• AU sizes compared to US kids’ sizes often use the same number, but US toddler sizes add a “T.” In other words, an AU kids’ 4 is typically a US 4T, while kids’ shoe sizes usually increase by one size from AU to US.

Australian and US sizing systems developed independently on opposite sides of the globe, which means an AU size tag rarely matches its US counterpart. In this guide, we break down the exact AU size to US conversion rules for clothing, shoes, bras, and kids’ wear. This will help you build highly reliable size charts that reduce returns and boost customer confidence.

How Do You Convert an AU Size to US Size?

Australian women’s clothing commonly uses numbers that align with UK retail charts, whereas the US established its own unique set of standards. Consequently, there is no single “magic number” you can subtract to convert everything in your store.

AU to US Women’s Clothing Sizes

For women’s apparel, the general rule of thumb is that the US size is typically four numbers lower than the Australian size. For example, an AU size 8 generally translates to a US size 4. This is because Australian sizing aligns closely with UK sizing standards, which carry the same offset from US brands.

However, this simple “minus four” rule is not foolproof. The rise of vanity sizing across different brands can throw off the math entirely. That’s why publishing a complete size conversion chart is far safer for your customers than simply telling them to subtract four from their usual size. 

AU to US Men’s Clothing Sizes

Men’s clothing relies less on direct size conversion. Tops in both countries use labels such as S, M, and L, but the body measurements assigned to each label vary by brand.

Men’s pants are usually easier to match because sizing is based on waist and inseam measurements. Australian brands may list these measurements in centimeters, while US brands commonly use inches. For example, an 82 cm waist is about 32 inches, and an 81 cm inseam is about 32 inches. A shopper with those measurements would typically look for US pants labeled W32 L32.

To make shopping easy for your shoppers, publish chest, waist, and inseam measurements in both inches and centimeters. This allows international buyers to quickly verify their size without needing a calculator. 

Are AU and US Shoe Sizes the Same?

AU and US shoe sizes convert differently by gender because Australian men’s sizing follows the UK scale while women’s sizing aligns with the US scale.

AU to US Women’s Shoe Sizes

For adult women’s footwear, the sizing systems are generally identical, meaning an AU size 8 is equivalent to a US size 8. However, variations in shoe width and the shape of the manufacturer’s “last” (the foot mold used to build the shoe) can still affect how they feel on a foot.

To help customers understand these minor differences, encourage them to read customer reviews. Adding user feedback that notes whether a style runs narrow, wide, or true to size gives shoppers extra confidence when the numeric sizes look exactly the same.

AU to US Men’s Shoe Sizes

Adult men’s sizes commonly shift by one full size because Australian men’s shoes also utilize the UK numbering system. Because the UK scale sits one size below the US system, an AU men’s shoe size 9 typically converts to a US men’s size 10.

A handful of modern Australian footwear brands have started labeling their products with US sizing to cater to global audiences. Always confirm which scale your specific manufacturers use before you finalize the conversion charts for your store. 

What’s the Difference Between AU and US Bra Sizes?

AU and US bra sizing is notoriously tricky, and converting them internationally requires looking at the underbust band size and the cup letter. While the band number changes consistently across every single conversion, the cup letter only starts to differ once you get above a standard D cup. 

AU to US Bra Band Sizes

Australian bra bands are commonly labeled with numbers such as 8, 10, 12, and 14, while US bands use numbers such as 30, 32, 34, and 36.

A common way to convert the bra size label is to add 22 to the Australian band number. For example, an AU 12 band generally corresponds to a US 34 band.

Keep in mind that this calculation converts the labels rather than the shopper’s exact underbust measurement. A US 34 doesn’t necessarily mean the wearer measures exactly 34 inches under the bust. Measuring methods and fit can vary by brand, so customers should compare their underbust measurement with the manufacturer’s size chart before choosing a size.

AU to US Bra Cup Sizes

Cup letters commonly align from A through DD in many AU and US charts. Above DD, brands use different naming sequences. For example, one brand may convert AU 12F to US 34G, while another may use US 34F. Shoppers should use the bra manufacturer’s complete international chart for fuller cup sizes. 

Because this split can easily confuse shoppers, it’s best to design your ecommerce store’s AU to US size chart to show complete, pre-paired band-and-cup sizes (like “AU 12E / US 34DDD”) rather than forcing customers to cross-reference separate band and cup tables.

Are US and AU Kids’ Sizes the Same?

Because Australian children’s fashion historically takes its cues from British standards, merchants often ask if US and UK (or AU) kids’ sizes are identical. While both systems use age-based numbering as their foundation, there’s one key labeling difference to keep in mind: US toddler sizes feature a “T” next to the number. For instance, an Australian size 4 corresponds directly to a US size 4T. 

By pairing each numeric label with a clear height range, you ensure parents can confidently pick the right fit. 

AU to US Kids’ Shoe Sizes

Australian kids’ shoe sizes follow the UK sizing scale, which typically sits one size below the US scale. For a direct conversion, your customers will generally need to size up by one full size when moving from an AU shoe size to a US shoe size. For example, an AU kids’ size 9 corresponds directly to a US kids’ size 10.

Make AU Size to US Conversions Easier With Kiwi Sizing

Manually updating static charts is a major headache for growing ecommerce brands. Kiwi Sizing replaces busy tables with dynamic, interactive tools right on your product pages. This Shopify app automatically displays inches or centimeters based on where your customers live, while the smart AI recommender calculates their ideal fit in seconds.

Stop letting sizing confusion drive up your return rates. Simplify your AU to US size conversions and scale your global sales today. Install Kiwi Sizing, the premier Shopify size chart app built to help your international customers buy with confidence.