What is the Ideal Fin Size?
The fins on the surfboard have a big impact on a number of things, including the manoeuvrability and stability of the surfboard. This article will briefly go over basic information regarding the size and weight of FCS and Future fins.

FCS Fins
SMALL (S) = 55-70 KGEXTRA SMALL (XS) = Under 55 KG
MEDIUM (M) = 65-80 KG
LARGE (L) = 75-90 KG
EXTRA LARGE (XL) = Over 85 KG

FUTURE Fins
EXTRA SMALL (XS) = 34-53 KG
SMALL (S) = 48-70 KG
MEDIUM (M) = 65-88 KG
LARGE (L) = Over 80 KG
Advice
When determining the ideal fin size, the fins' weight is a good starting point in deciding what will work well for beginners or intermediates. However for the more exploratory surfers, the ideal fin size is typically determined by your style of surfing. For example smaller fins may be used in smaller surfers for a looser feel alternatively for power surfers larger fins may be put in the board for extra traction.
You may notice each surfer has a different fin set up. Some go for the single fin, others have up to 5 fins. The different set ups represent the different style of surfing and the amount of stability and maneuverability each surfer desires.
Single Fin -
Single fins are often found on longboards or beginner boards. They provide stability and control. They cut down the sharp turns and movement and help produce sweeping turns and straight-lined charges.
Twin-fin boards are harder to control in large waves but offer good maneuverability in smaller conditions. They are usually found on shortboards and fish boards, because the two-fin setup encourages speed.
Two Fins-
Two fins are often harder to control in bigger surfs. In the smaller swells they allow a great range of movement and are therefore commonly found on shortboards and fish boards where speed is desired.
Three Fins-
Three fins is the most common set up and can be found on any type of board. It is the best performer in every different surf conditions. It allows for a stable and maneuverable board.