Aspect ratio is the one figure on a foil spec sheet that means the same thing at every manufacturer, because a ratio survives the fact that brands measure area differently. It is also routinely over-read.
Same area, different wing
Aspect ratio is span squared divided by area. Two wings can hold identical area and sit at opposite ends of the range:
What the name on the wing does not tell you
Across the 1,003 wings on this site from 23 brands, family names are not a reliable guide. Of the 48 wings whose family name says HA or "high aspect" and whose aspect ratio the data can place in a band, 21 are not in a high-aspect band. Aspect ratios have crept up industry-wide, so plenty of wings sold as carving foils today sit where "high aspect" sat a few seasons ago.
Nor is aspect ratio constant within a family. Naish's Jet HA runs from 10.2 down to 6.8 across its own sizes; Takuma's Kujira II runs the other way. "I ride the HA" tells you nothing without the size.
Where it stops predicting
Turning radius depends at least as much on span as on aspect ratio, and span varies more than twofold inside a single band. A large wing low in the ramp is a lifting foil that happens to share an aspect ratio with a surf wing. Read a band together with the wing's area, never on its own.
771 of 1,003 rows here do not state whether their area is projected or flat — a routine 3–8% difference, which is wider than many of the comparisons the plot gets used for. Treat a small area difference as noise.
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Updated 2026-08-11