How this guide was built

Across the typical adult range (roughly 170–185cm), weight is what actually moves you between sizes — height on its own barely shifts the recommendation, which is why most rows above read the same. Height only starts to matter at the shorter and taller extremes, where certain weight combinations become uncommon (greyed out above) rather than genuinely changing which size fits.

The weight bands are calibrated against our high-hip size chart (XS 72–76cm through XL 92–96cm) and checked against a real reference fit: 175cm, medium build — 75–78kg sits comfortably in Medium underwear both ways, but the same person needs to size up to Large in swimwear once they cross 78kg, since swim fabric has far less give. XXL is extrapolated — it continues the same 5cm high-hip / ~8kg weight step pattern as the sizes above it, since it isn't on the official chart yet. Worth confirming against real garment measurements before this goes live.

If you're between sizes: for swimwear, size up — compression fabric won't forgive a tight fit. For underwear, your usual size is fine; the stretch cotton/modal blend adjusts with you.

On build: the athletic/fuller adjustment shifts the weight bands by ±5kg — an estimate based on how muscle vs. fat typically distribute around the waist, not a measured biometric curve. It'll nudge people in the right direction, but it's the roughest part of this model. If you ever collect self-reported build alongside exchange data, that's the input that would let us replace this estimate with something real.

If your build is unusually broad, narrow, or you fall right on a boundary, the most accurate method is still a direct high-hip measurement — see our tape-measure guide for that.