Swimwear Size Calculator: Bikini to One-Piece
This swimwear size calculator factors the wet-fit problem most charts ignore: swim fabric stretches when wet, so the right dry size is 0.5 smaller than your typical apparel size. Enter bust, waist, hip and the tool returns bikini, tankini, and one-piece sizes for US, UK, EU, AU. Use the calculator below to get your exact fit in 30 seconds.
How it works
Measure yourself
Take your bust, waist, and hips with a soft tape. See the full measurement guide.
Enter the numbers
Type your measurements into the calculator above. Pick inches or cm — the tool converts both ways.
Get your size
Match the result against the brand's chart and order with confidence.
Women's tops & dresses — bust-driven sizing
| Size | US | UK | EU | Bust |
|---|---|---|---|---|
| XS | 0–2 | 4–6 | 32–34 | 31–33" |
| S | 4–6 | 8–10 | 36–38 | 33–35" |
| M | 8–10 | 12–14 | 40–42 | 35–37" |
| L | 12–14 | 16–18 | 44–46 | 38–40" |
| XL | 16–18 | 20–22 | 48–50 | 41–43" |
| XXL | 20–22 | 24–26 | 52–54 | 44–46" |
Frequently Asked Questions
Why does swimwear feel tight in store but loose at the beach?
Swim fabric stretches 1–2% when wet. Sizing 0.5 smaller than your usual apparel size compensates.
Should I order bikini top and bottom in the same size?
Often no — pick top by bust and bottom by hip independently. Brands selling separates make this easy.
How do one-piece swimsuits fit relative to bikinis?
One-pieces add torso length to the equation. Tall frames may need to size up to clear the shoulder; petite frames size down.
What if I'm between bikini sizes?
Size down for athletic styles, size up for ruched or fuller-coverage cuts. Stretch fabric handles both.
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