Carabiner shape determines how loads distribute across the metal, where the rope sits in the basket, and how easy the carabiner is to clip and unclip. Most climbers learn one or two shapes (the pear-shape locker for belaying, the asymmetric D for everything else) — but understanding all four shapes helps you build a versatile, weight-efficient rack.
This page covers the four main carabiner shapes in detail, with a quick decision tree at the bottom for choosing the right shape per application. For the broader carabiner reference (gates, materials, kN ratings), see our carabiners explained guide.