Swimwear Sizing Explained: US vs AU vs UK

Ever wondered why you’re a 10 in Sydney but a 6 in New York? Let’s dive into why swimwear sizes are confusing and how to find your perfect fit.

Quick Size Conversion Chart

Use this table to find your international equivalent. Note that AU and UK sizing are generally identical, while US sizing runs smaller numerically.

International	AU / NZ / UK	USA / CAN	Bust (cm)	Waist (cm)
Extra Small (XS)	6	2	80-82	62-64
Small (S)	8	4	83-85	65-68
Medium (M)	10	6	88-90	70-73
Large (L)	12	8	93-95	75-78
Extra Large (XL)	14	10	98-100	80-83

Why is Swimwear Sizing So Confusing?

If you've ever felt like your body is "between sizes," it’s not you—it’s the industry. Here are the three main reasons swimwear sizing feels inconsistent:

1. Regional Standards

The US uses "Vanity Sizing," where numbers have decreased over time to make shoppers feel better. AU/UK sizes have remained more traditional, meaning an AU 10 is cut tighter than a US 10.

2. Fabric "Recovery"

Swimwear is made of Nylon or Polyester blends. Nylon is softer with more "give," while Polyester is chlorine-resistant and "firmer." A size 12 in Polyester will always feel tighter than a size 12 in Nylon.

3. The Grading Process

Most brands design for a size 8 and just "stretch" the pattern for larger sizes. At Splash Swimwear, we look for brands that fit-test on real bodies to ensure the proportions actually work for your curves.

"Pro Tip: If you are between sizes, always size UP in swimwear. Most fabrics shrink slightly when exposed to sun and salt, and a tighter suit can cause 'dig-in' at the hips and shoulders."

Find Your Perfect Fit in 3 Steps

📏 Bust: Measure around the fullest part of your chest.
📏 Waist: Measure the narrowest part of your natural waistline.
📏 Hips: Measure the widest part of your hips (usually across your seat).