Underwear Size Calculator: Brief, Boxer, Trunk
This underwear size calculator runs entirely in your browser — no data is sent to a server, no measurements are stored. Enter your waist and hip and get sizes for briefs, boxers, trunks, thongs, and bikini-cut for both men and women. Returns US, UK, EU sizing. 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
Are men's and women's underwear sizes the same scale?
No. Men's use waist in inches (S=28-30, M=32-34, L=36-38). Women's use either S/M/L or numerical (4, 6, 8) keyed to hip.
Should I size up for boxer briefs vs briefs at the same waist?
Match exactly. Boxer briefs and briefs from the same brand use identical waist sizing. The leg cut differs, not the band.
How do I measure for thong sizing?
Hip is the primary number for thongs and bikini-cut. Waist matters less because the band sits low.
What if I'm between two underwear sizes?
Size up. Underwear waistbands stretch over time — sizing up by 1 keeps you comfortable longer. Size down only if you want compression-fit.
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