I have more carabiners than any men could possibly use. They range in quality from dollar store junk to the climbing carabiners I trust my life with. After looking into the weight ratings of cheap carabiners I don’t know why I still have them. So how much weight can a carabiner hold?
Lets start by clarifying that carabiners are rated by force, since they handle falls instead of a static load. Carabiners are rated in kilonewtons (abbreviated kN). Most climbing carabiners have a 24 Kilonewton rating which means they can handle 5,400 pounds of force. For a carabiner to be rated for climbing it needs to hold at least 20kN (4500lbs) on its vertical axis. Cheap unrated carabiners aren’t meant for climbing and they won’t be able to handle more than 200-300 pounds.
Today I’m making this post to try and clear up some of the confusion surrounding carabiners. It mostly boils down to understanding the difference between rated/nonrated carabiners and figuring out what the weight rating means. What does kN mean and what’s considered a good weight rating?
Check out the Petzl Triact carabiner, which is easily my favorite carabiner. It has a 23kN safety rating which means it can hold 5,175 lbs on its vertical axis. At its weakest point (horizontal load) or with the gate open it can hold 1,575 lbs (7kN). A fall with that much force would seriously injure you so that’s stronger than any climber could possibly need. Most falls average 2.4kN (540lb) of force and serious falls rarely exceed 5kN (1,125lb) according to the UIAA.
Remember that you should never rely on a cheap unrated carabiner. Carabiners without weight ratings should be treated like novelty items to hang lightweight junk in the garage or around the house.
How Much Weight Can a Carabiner Hold?
Everybody that’s ever purchased a carabiner has asked the same exact question. I wonder how much weight this carabiner can hold? Climbers are putting their life on the line so they want to make sure their gear won’t break under pressure.
Every UIAA rated carabiner should have a safety rating imprinted somewhere on its body. The picture above shows the safety rating of a Petzl Triact Carabiner, which is easily one of my favorite carabiners. It has a 23kN (5175lb) safety rating on its major axis (vertical load), 8kN (1800lb) safety rating on its horizontal axis, and 7kN (1575lb) with the gate open.
The vast majority of climbing carabiners fall into the 23kN-27kN (5175lb-6,075lb) range on their vertical axis. To qualify as a climbing carabiner you need to have at least a 20kN (4,500lb) vertical rating. At their weakest point they can usually handle about 1/3 of their total safety rating.
Cheap carabiners usually aren’t rated and if they are the ratings don’t come close to meeting UIAA standards. Major falls can generate upwards of 6kN of force so a climbing carabiner needs to handle that at its weakest point.
Carabiner Safety Ratings Are Measured In Force Not Weight
Americans measure weight in pounds and most other countries are familiar with kilograms, but unfortunately that’s not how carabiner safety ratings are measured. Carabiner weight ratings are measured in kilonewtons which is abbreviated kN.
They use kilonewtons, because the safety rating is a measure of force instead of weight. I’ll get further into that below, but here’s a simple conversion: 1 kilonewton is approximately 225lbs or 100kg of force. Just remember that you’re not dealing with a static load when you fall since force is equal to mass times acceleration.
The UIAA standard for climbing carabiners is 20kN, which is about 4,500lbs of force. That’s the bare minimum for a carabiner to be safe for climbing. You should be able to attach 4,500lbs to a climbing carabiner and hoist it up without any problem, but a 1ft drop would most likely rip it apart.
The vast majority of climbing carabiners have a 24-25kN safety rating on its vertical axis and 7-8kN of at the weakest point (horizontal load or open gate). So the weakest point of a carabiner has a similar safety rating to climbing rope which handle about 9kN of force.
That’s really impressive if you ask me! A cheap Black Diamond Rocklock Screwgate carabiner costs less than my typical order at Chipotle and can hold up my Honda Accord. Expensive carabiners with fancy locking mechanisms like the Petzl Triact Autlocking Carabiner have a slightly higher 27 kN safety rating, but the difference is negligible in most situations.
Why Is A Carabiners Safety Rating Higher Than Other Gear? (Understanding Horizontal Load)
Why is the minimum safety rating for carabiners 20kN when the rest of my gear is closer to 9kN? It’s important to understand that carabiner safety ratings are for its vertical load. Carabiners are designed so the rope naturally slides into the top and bottom corners of the carabiner, because that’s its strongest point. That’s where the 20+ kN safety rating is measured at.
UIAA chose the 20+ kN rating for a very important reason. They chose it because a carabiners horizontal load is usually 1/3 of the vertical loads safety rating. So a typical 24kN climbing carabiner can handle an 8kN horizontal load on its major/minor axis. An open gate has a similar effect on the vertical load reducing it to about 1/3 of the total rating.
This puts the weakest point of the carabiner in line with every other piece of climbing equipment. Most climbing ropes are rated at just under 9kN so they can handle the same amount of force as the carabiner at its weakest point. If the vertical load on a carabiner was 9kN like most ropes, the horizontal load would only be 3kN. It wouldn’t take much to break it with an awkward load.
Everybody understands the concept of weighing an object to get its weight. I step on a scale and it gives me a reading of how much I weigh (usually more than I’d like). We understand how weight works, but trying to calculate force is out of most peoples wheelhouse.
A 200lb person that falls 6ft generates 2,400 lbs of force, which is more than enough to cause injury. Experienced climbers know how to minimize force so there’s never more the 5kN of force on their gear or 2.4kN of force on the climber/belayer. You really don’t need to understand impact force, but here’s a brief overview.
Force equals mass multiplied by acceleration. So you have to multiply the mass of the person (plus gear) by the acceleration of gravity which is 9.8m/s squared. A 200lb person falling 6ft would generate just under 2000lbs of force when you add in a few lbs for gear. Obviously, that’s in a freefall situation, which should never happen with safety gear.
With proper safety techniques a climber should never take that hard of a fall, but you can see how mass/acceleration play a role in total force. The average fall results in 2.4kN (540lbs) of force and according to the UIAA serious falls rarely exceed 5kN (1125lb) of force. A 5kN fall would cause major whiplash and most likely lead to injury, but it would rarely lead to death.
Are Old Carabiners Safe To Use?
It’s important to understand that the rating on your climbing gear is only for brand new gear. Heavy impacts will slowly wear away at the gears safety rating. That’s why most carabiners are rated for 25kN instead of the 20kN recommended by the UIAA safety committee. They want to have some wiggle room so the carabiner will always meet safety ratings.
When it comes to climbing gear carabiners are generally seen as the weak link. Ropes can usually handle more force than a carabiner with an open gate or a horizontal (major/minor axis) load. With that being said, climbing carabiners rarely have catastrophic failures where they completely snap apart.
So how do carabiners wear down? The carabiners gate is by far the weakest link. It’s gate wares down and it won’t snap back into place easily. You may also run into issues with the locking mechanism. Once the gate wears down, you’re more likely to not completely tighten and close the gate. A carabiner with an open gate has an 7-8kN impact rating.
As you wear out a carabiner it will slowly grind away at the aluminum/steel and chip away at the protective coating. The carabiner will start to develop tiny little spurs and ridges that can catch on your rope causing excess friction slowly wearing away at the rope.
How Much Force Can Climbing Exert On Gear?
The UIAA has done extensive testing on the forces generated by falls and they’ve determined that maximum of amount of force a fall can generate is 5kN. Petzl did similar tests and got up to 6kN of force. This is pretty close to the horizontal and open gate load standards set by the UIAA, which is why most companies increase quality to give some wiggle room.
Just remember that your gear may be able to handle 6kN of force, but that doesn’t mean your body can. It would take a very nasty fall to generate 1,350 lbs of force. You would be falling fast and most likely end up with whiplash and other injuries.
What About Cheap Chinese Carabiners?
You should never trust your life to a cheap carabiner without a safety rating, but that doesn’t mean they’re completely useless. I constantly use the cheap $1 carabiners that you can pick up at any dollar store, Walmart, etc. I’m talking about the ones that have “Not For Climbing” stamped on the sides.
I didn’t realize how cheap those were until I used one to attach my cousins bulldog to his wire lead. He has a chubby 50lb bulldog so I didn’t think it would a problem. It seemed to be working out well, but 20 minutes later a squirrel dropped into the yard and the dog took off. My dollar store carabiner snapped instantly and the dog ran off into the woods. He came back right right away, but that reminded me of those old physics lessons I forgot about in college.
Force equals mass times acceleration. A 50lb bulldog running at 15mph can generate a way more force than you would think. I’m too dumb to do the math, but it was enough to snap a carabiner that could hold my fat butt up in a hammock. Most rock climbing falls generate a falling force between 500 and 1250lbs so that’s way more than a cheap carabiner could handle.
If your carabiner doesn’t have a weight rating you can assume it can’t hold more than 200-300lbs. You can find budget carabiners that have 12KN safety ratings, but those aren’t strong enough for climbing. They’re great around camp, but It’s worth spending the extra money (like a $4 difference) on a budget rock climbing carabiner made by a trusted company like Black Diamond, Petzl, Metolius, etc.
You can find 25KN carabiners without locking mechanisms for less than $10 and ones with locking mechanisms for under $15. Cheap carabiners can handle the stupid stuff, but it’s worth spending the extra money on a handful of climbing carabiners to take backpacking.
I keep a handful of Black Diamond Rocklock Screwgate carabiners in my pack that I use for a wide range of things around camp. Carabiners aren’t just used for climbing. They get used with my hammock, hold up my bear bag, lock my tent zipper to keep the dog in, attach random gear to my pack, and for lots of random odd jobs..