Key takeaways
- A carabiner is a spring-gated metal connector — the universal link in a climbing system.
- Locking carabiners secure the gate for critical connections (belay, anchors); non-locking are used in pairs on quickdraws.
- Common shapes: D and offset-D (strong, efficient), HMS/pear (wide, for belaying), and oval (versatile).
- Carabiners are far weaker when loaded across the minor axis or with the gate open — always load them correctly.
From the German Karabinerhaken, 'carbine hook', used to clip a carbine to a strap.
How a carabiner works
A carabiner is a metal loop with a spring-loaded gate on one side. Pressing the gate open lets you clip in a rope, sling, or another carabiner; releasing it snaps shut so the connection can’t fall out. The solid side opposite the gate, the spine, carries most of the load. Climbing carabiners are forged from aluminium alloy and stamped with their strength ratings in kilonewtons.
Locking vs non-locking
A locking carabiner adds a sleeve — screw-lock (screwgate) or auto-locking — that secures the gate for critical connections like belaying, rappelling, and anchors. Non-locking carabiners, including light wiregates, are used where the gate can’t accidentally open, most often as the two clips of a quickdraw.
Shapes and types
- D / offset-D — pushes the load onto the strong spine; the most common all-round shape.
- HMS / pear — a wide top for belaying and the Munter hitch.
- Oval — symmetrical, smooth-loading, good for aid climbing and racking.
A climber clips a quickdraw to a bolt with one non-locking carabiner and the rope into the other, but uses a locking carabiner to attach their belay device — because an open gate there could be catastrophic.
The bottom line
The carabiner is the humble connector that holds the entire climbing system together. Choosing the right type — locking for critical links, the right shape for the job — and always loading it correctly along its strong axis is basic, essential gear knowledge for any climber.
Frequently asked questions
What is the difference between a locking and non-locking carabiner?
A locking carabiner has a sleeve or mechanism that secures the gate shut, used where an accidental opening would be dangerous (belaying, anchors, rappelling). A non-locking carabiner has a simple spring gate and is used where it can't easily come unclipped, such as the two ends of a quickdraw.
How strong is a carabiner?
Climbing carabiners are rated in kilonewtons (kN) and typically hold around 20–24 kN along the major axis with the gate closed — well beyond any fall force. But strength drops sharply if loaded across the minor axis or with the gate open, which is why correct orientation matters.
What shape of carabiner should I use?
D and offset-D shapes are the strongest and most efficient for general use; HMS (pear-shaped) carabiners have a wide top for belaying and Munter hitches; ovals are symmetrical and good for aid and racking gear. Most climbers carry a mix.
Sources
- Connectors & carabiner standards — UIAA
- Carabiner technology — Petzl