Sizing & compatibility

Match your board fin system to the right product, then size by surfer weight and board volume.

Fin systems

• US Box: longboards and most mid-lengths use a single 10.5-inch centre box.
• Futures-style: twin, keel, quad, side-bites — most modern shortboards and fish.
• FCS I-style: older twin / keel / quad / side-bite tabbed system. Different base, same feel.

Sizing

Read our full Feel Guide for the four levers (base, depth, sweep, foil) and how each affects how a board surfs. Quick rules of thumb:

• Single fins (longboard / mid-length): 9-inch is a safe all-rounder. Lighter surfer or smaller wave: 8.5". Heavier surfer or trim-on-the-nose: 9.5".
• Twin fins (fish / mid-length): pair size scales with board volume. Most fish twins are 4.5-5" base.
• Keel fins: drop into any twin tail. Pick the same base/depth as twins for the same volume.
• Quads: full-size quads for shortboards, mini-quads for shorter or asymmetric boards.

Not sure?

Use the Fin Finder. Tell us your board and feel; we will match it to a fin in 30 seconds.

Still stuck? Email us with your board dimensions; we will recommend.