Carabiner Strengths Explained & Explored

To ensure your new carabiner is strong enough to use rock climbing, make sure it is CE and/or UIAA certified from a known climbing manufacturer. That’s literally all you have to do to ensure your carabiner is strong enough to climb on and we’ll use the next 1,200 words to explain why.

Carabiners rated for climbing have minimum strength requirements to ensure the gear will not break when used properly. Climbing carabiners are rated in 3 orientations.

Major Axis

This is the strongest orientation and the way carabiners are designed to be loaded.

Open Gate

While climbing, carabiners lying against the rock can be opened slightly as they move across an uneven surface. A carabiner can also open slightly during a fall as the ‘biner starts to vibrate, dispersing the energy (also called “gate flutter“). A weak gate closure (due to a poor/failing spring or an over-stressed wire) could also leave the gate ajar.

Minor Axis

Carabiners are not intended to be loaded along the minor axis (cross-loaded), but it’s possible for a carabiner to unintentionally rotate during use, particularly during belay. Of all accidental misuses of a carabiner, cross-loading is the most frequent suspect, which is why there is a rating for it.

Note: Generally wire gates are stronger than solid gates in this orientation. During the test, the wire gate bends, absorbing some of the force, as compared to a less pliable solid gate.

How to identify a certified carabiner

On the spine of every certified carabiner there will be a CE and/or UIAA icons. They will either look printed (laser etched) or forged into the body of the carabiner.

Laser etched CE and UIAA certified carabiner

Forged CE certified carabiner

Note: UIAA certifications are optional for manufacturers. CE certifications are mandatory to sell products in Europe. A carabiner is not stronger/weaker if it only has one rating. CE certification standards are often based on UIAA recommendations.

How strong are certified carabiners?

Carabiners certified for climbing by CE and/or the UIAA are exceedingly strong and will not break when used as intended. In their optimal direction of use (loaded along the major axis) most carabiners are certified for a minimum of 20 kN.

A real climbing fall has a maximum force of 5kN.

– The UIAA

Minimum UIAA Carabiner Strengths

UIAA carabiner tests are done with static drops that far exceed the force capable in an over-exaggerated climbing fall. If you want to know the exact mechanisms and procedures used for testing, check out the official UIAA website.

Major Axis

• All carabiner shapes except ovals: 20 kN
• Oval carabiners: 18 kN

 Open Gate

• D, Offset D carabiners: 7 kN
• HMS / Pear (belay carabiner) shapes: 6 kN
• Oval carabiners: 5 kN

Minor Axis

• All carabiner shapes: 7 kN

The UIAA emphasizes

Karabiners never break when tested with a free falling mass.

The falling climber is also free to move laterally and induce less vibrations and a soft rope braking from the belayer… The UIAA standard for climbing karabiners demands a static strength of more than 20kN. This value corresponds to holding a mass of about 2 tons before breaking. 20kN is more than the worst conceivable fall in a climbing accident.

This excerpt comes from a full article that addresses dynamic versus static testing. You can click to read the article in its entirety.

Carabiners can break in-use

While it is possible to break a carabiner, it only happens when the gear is not being used as intended.

In rare cases when carabiners have broken in-use, virtually all of them have broken when the nose was loaded. The nose is the weakest point of the carabiner and since carabiners are not designed or intended to hold falls on the nose (and it is rare that this happens), there is no certified rating.

A carabiner may break if…

• its nose gets caught on a bolt hanger or piece of gear and then loaded (see photo above). Typically this happens when a notched nose carabiner gets hooked on a bolt hanger. Black Diamond wrote a Quality Control post about this situation and concluded that the nose of a carabiner may fail at less than 10% of its rated closed gate strength (<2 kN / 227 kg), forces achievable in a bounce test.
• the carabiner rotates and then becomes cross-loaded. To learn more you can read a 2013 accident report where a keylock carabiner broke because a fall was taken and the carabiner was not weighted on the major axis. The climbers take-away points included, “double-check your draws to make sure they are hanging properly and not snagged or twisted.”

It is somewhat unfortunate that nose strength is not a rated part of the carabiner since it’s the weakest area. That said, it’s worth noting that a carabiner should never be loaded in this orientation during proper use and it rarely happens (much less than cross-loading and gate flutter). To test and certify the strength of the carabiners nose, it would require additional time and money, making gear more expensive without adding a substantial safety benefit.

The main reason WeighMyRack doesn’t filter on carabiner strengths is because it doesn’t make a noticeable difference while climbing. Yes, carabiners with higher strength ratings will be stronger, but in normal use even the weakest rated carabiner will perform admirably.

It’s not the strength ratings that will determine the breaking point of your climbing-rated carabiner, it’s how you use it.

Gear is strong and can take a lot of abuse

There are tons and tons and tons of gear videos online showing huge whippers, and these are just the falls caught on video. Rock & Ice actually dedicates a section of their website to Weekend Whippers and makes a yearly compilation of the worst falls, almost all over 40 feet of terror. Normal climbing does not include 80 foot lead falls where gear has proven to survive.

These are not average scenarios and each time the gear performs as intended during seemingly catastrophic falls.

Instead of looking at strength ratings…

Before you buy

• Only choose carabiners that are certified for rock climbing (CE / UIAA). Carabiners/hardware that are not certified for climbing fails at low forces.
• Always buy gear from known climbing manufacturers. There have been cases of Chinese knockoffs that may exhibit a slightly narrower CE logo that is nearly identical to the official CE rating (for “European Conformity”) but the knockoff actually means “China Export.” There are also folks looking to jump on the exploding climbing market who are importing unbranded gear to sell cheaply online. Neither of these cases can be trusted to be officially CE / UIAA certified.
• Look the nose of each carabiner: clean nose angles, keylock carabiners, and shrouded noses will all reduce the ability for the carabiner to snag and become loaded in an unintended orientation.
• If you’re worried about gate flutter, use wire gate carabiners on the rope-end of your quickdraws. The lighter wire gate is also less prone to whiplash that may cause a gate to shutter.
• Most climbers find full-size carabiners are easier to hold and clip, reducing the chances of falling on a snagged nose.
• You may also want to use full-size carabiners because your brain intuitively believes they are stronger. Nothing is worse than questioning your gear, and mini-carabiners can look questionable even though they can be just as strong.

After you buy

• It’s important to inspect and clean carabiners to ensure their longevity. A sticky gate has a much higher chance to cause serious issues. If the carabiner gate feels weak, retire it.

While you climb (tips from Rock & Ice)

• When extending trad draws, remove any loops that develop.
• Rack long slings fully extended and fix the lower carabiners to prevent cross-loading.
• Use locking carabiners on critical pieces.
• Avoid kicking or shifting your draws as you climb past them.

Bottom Line

It can be frustrating to be without a concrete answer to the question, “What is the most ideal strength rating?” All things being equal, higher strength ratings are better. However, the design of a carabiner’s nose (angle, type, shroud), and using the gear correctly (orientated in an optimal direction) makes a bigger impact on the safety of a carabiner versus comparing the individual strength numbers. Ultimately, any CE / UIAA rated carabiner coming from a known climbing manufacturer is safe to climb on.

This post was inspired by a question we received asking, “What would be a good guide for a safe minimum strength numbers regarding the ratings?”

In addition, Mike Kann helped beef up our post by offering some great caveats around open gate strength, statistics, and knockoffs.

If you have gear questions, feel free to reach out publicly via the comments below, or privately by using our contact form.