I recently suffered one of life’s greatest indignities — I couldn’t open a stubborn pickle jar. I gave it all of my might. I tried one of those rubber jar-opener thingies. I screamed multiple obscenities at it. I even gave it all of my might while using one of those rubber jar-opener thingies and screaming obscenities. And yet, nothing. Admittedly, I am no Thor, but I swear I have at least the bare minimum amount of strength required to uncork a pickle jar.
Maybe it was the humiliation talking, but I almost immediately became fascinated with figuring out exactly how much strength that is. Did it require the muscles of a Norse god/Avenger? Should I be hitting the gym just so a pickle jar no longer poses such a formidable challenge? Are a majority of other human beings unable to muster such power?
For answers, I turned to mathematician James Hind from Nottingham Trent University, and like he has in the past, he got right on the case.
After doing some digging and calculating, Hind explains that the reason why jars are tough to open is because food manufacturers make a point to minimize the amount of air that gets in them. “They tend to fill the jars at a warm temperature, so that when they cool, the small amount of air at the top also cools,” Hind tells me. “As it cools, it shrinks a little, forming low air pressure. This reduces how much air there is to oxidize the food and keeps the lid on tight.”
Thus, after you’ve bought the jar and brought it home, it’s tough to remove the lid, not only because it’s screwed on tight, but because you’re working against the vacuum that was created by the change in air temperature when the pickles were put in the jar. “As you twist the lid to open it,” Hind explains, “you’re having to raise the height of the lid, so you’re making the jar a bit bigger. This means you’re lowering the pressure in the jar even more, and you have to fight against the suction force that’s pulling the lid back down.”
Once you twist the lid enough, the spiral on the lid no longer fits the spiral on the jar perfectly, and air rushes into the jar. “That pop you hear is a pressure wave in the air from this rebalancing,” Hind continues.
Given all that, how much strength does it take to perform such a feat? Well, Hind explains that, turning force is called “torque,” and its formula is T=F×r×sin(θ). In that equation, Fis the force you apply, r is the radius (i.e., the distance from the center of the jar that you apply the force), and theta (θ) is the angle between the force you apply and the center of the pickle jar lid.
Now, if you’re mathematically illiterate like me, I may have lost you, but fortunately, Hind included a diagram that makes it a little more clear (I think):
There may be some variety when it comes to pickle jars, but not a lot, so I suggested to Hind that he base his calculations on a 24-ounce jar of Vlasic pickles — in part because that’s what I had in my fridge, and in part because I love that Groucho Marx-looking stork on the jar.
“A 24-ounce jar is about 41.6 cubic inches,” Hind says. “Including the small air gap at the top, we’ll call that 48.1 cubic inches, which corresponds to a jar that is five inches high and that has a lid three-and-a-half inches across. If you’re just grabbing hold of the lid, r is 1.75 inches. Raising the lid by one-eighth of an inch will let air in and open the jar.”
Per Hind, before the air came in, there was about 6.5 cubic inches of air at the top of the jar, but once you popped it open, it became 7.7 cubic inches, which caused the air pressure to drop to about 85 percent of what it was before. He says that this difference in pressure would take 21 pounds of force to achieve, but since we have to turn the lid there’s additional strength required. To get that number, he says that you plug the 21 pounds of force calculation into the torque equation, which results in 36.75 pounds.
So, there’s my/your answer: It takes 36.75 pounds of force to open a pickle jar.
Which, I guess is satisfying to know, but what the fuck is a pound of force anyway?
I did some Googling and discovered that it takes about eight to 10 pounds of force to open a front door, and about 20 pounds of force to open a can of soda. Getting closer to pickle-jar-opening territory, I read that it takes 35 pounds of force to break two boards of wood in half. Still, I’ve never broken two boards in half and I don’t really know what that means in practical terms. I did read, however, that if you press hard on a bathroom scale, the number it displays is how many pounds of force you’re exerting. So, if you’re super curious what 36.75 pounds of force feels like, go press on a scale and find out.
Something, though, was still troubling me. If just opening a door is 10 pounds of force and a soda can is a whole 20 pounds, why is it genuinely difficult for some people — read: me — to open a jar of pickles?
While Hind told me that strength and hand size are a factor in opening a jar — because they determine how much force you can exert and how well you can grip the lid — the existence of those rubber jar-opener thingies (or the more old-fashioned towel method) got me thinking that opening a jar is less about force and more about grip. And by that, I don’t mean grip strength, because you can still be as strong as a fucking bull and moisturize enough to have baby-soft hands. I mean the coarseness of your skin might be directly related to how well you can grip something — e.g., the lid of a pickle jar.
To confirm this theory, I turned to two of MEL’s in-house fitness writers and grip experts, Ian Douglass and Oliver Lee Bateman. “Yes, calluses and rougher skin make it easier to grip a thing. This is why heavy gripping leads to the development of calluses,” Bateman explains. As for Douglass, he offered up this delightful example: “If we coat the pickle jar in olive oil, it doesn’t matter if I’m Dwayne Johnson — I’d never be able to open it.”
And so, it might take 36.75 pounds of force to open a pickle jar, but someone’s strength is probably not the primary factor in their jar-opening abilities. It’s much more likely to have to do with the roughness of their skin.
In the end, then, I guess I don’t need to spend more time in the gym, I need to spend less time moisturizing.
Brian VanHooker
Brian VanHooker is a staff writer at MEL specializing in pop culture, food (especially pizza) and long form oral histories. He is the co-creator of the comic book "Barnum & Elwood" and "The Tramp," a comedy pilot starring John O'Hurley. He also hosts a TMNT interview podcast called "Turtle Tracks" and was once called a "Good Guy" by Mr. T.
