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How to Open a Can with a Key | Step-by-Step Guide

A key to open cans used to come attached to the top of the cans. It is nostalgic to remember these keys, but if you have never seen one, figuring out how to open a can with a  key is not the easiest.  Here is a step-by-step guide on how to do it.

How to Open a Can with a Key

  1. Remove the key from the top of the can.
  2. Insert the key into the opening on the side of the can.
  3. Twist in the opposite direction of the strip.
  4. Twist all the way around the can.
  5. Remove the top and enjoy.

There are different types of can openers, all with keys attached to them. All of these can openers are classified as different types of openers. You can also open a can with other items besides keys, such as a Chef’s knife and a spoon. If you have ever had a can of sardines, the can key probably comes to mind.

Can Being Opened With a Key

The Can Key

They can key is a classic way of opening cans of a square nature until the pop-top was invented. This key would come attached to the top of the can, and you would remove the key, insert it into the hole on the side of the can.

As you turned the key, it would tear the can away from itself, rolling up the aluminum with the key. The top was free to pull off, and the key had all of the aluminum rolled up on it from the can.

You simply throw the key and aluminum scrappings away with the can. This was the most common way to open cans before 1970. The cans were thinner and easier to open this way versus the church-key style from earlier times.

Some common items that would come in this type of packaging were nuts, corned beef, ham, bacon, Frozen Strawberries, and mostly anything in a can in the 1960s and prior.

Church Key

The church key is more of a bottle opener than an actual key to open cans. They are used mainly to remove bottle caps and puncture holes in flat-top cans.  On one side is a triangle-shaped point, with a small metal tab on the inside. The other side is a bottle opener.

Opening cans that hold liquid would be the best use for this type of can opener. These were used to open flat-top beers, and cans of condensed milk. A Steady hand is required to open other types of cans but is still easier than the original can key.

You place the top of the triangle-shaped tip on top of the top portion of the can. Fitting this snuggly against the top lip of the can, press upwards, creating a downward force against the top of the can. After poking a triangle-shaped hole in the top of the can, move slightly over, leaving a small space, and repeat.

When you make it all the way around the top of the can, you will see that the top resembles more of a star. If done correctly, there should only be a slightly thin tab of aluminum between the spaces. Insert the top of the triangle piece and pull upwards, breaking the small binds between the holes.


The P-38 was the standard issued key can opener for the military during world war 2, all the way until the 1980s, when the soldiers were issued C-rations.

The P-38 is still in production and usually handed out in rescue missions or when can food rations are needed to feed people in large groups. Disaster relief organizations issue these can openers at disaster sites to feed people with canned rations.  To use the P-38, you unfold the 95-degree angled blade and line it up on the lip of the can.

There is a small indent underneath the blade that the lip of the can will rest on. As you make your way around the entire can, you slowly puncture the top of the can with the blade that is fitted on the P-38. The flat end of the key doubled as a flathead screwdriver for minor instances.

 Military personnel used the P-38 for

  1. Opening c-rations
  2. An in-field screwdriver
  3. Letter opener
  4. Thread cutter
  5. Wire Stripper
  6. Pencil Sharpener
  7. Muddy Boot Cleaner
  8. Set Points on a car.

The P-38 was one of the most useful can keys ever invented.

Butterfly Opener

This one is most commonly misused because it’s similar to the bunker opener. The butterfly opener lays flat on top of the can lid. It has a tab on the edge to guide itself along the top of the can. You open the pliers, and place the top of the can towards the back part of the wheel arrangement.

The wheel is on the inside of the top portion of the can, and the church key penetrates the side of the can. As you turned the key, the church key cuts through the aluminum side of the can.

You can simply lift the lid off of the can.  The downside to this type of key is that is can be difficult to use, and most people just use it as a bunker opener until the blade dulls.

This is the most common can opener found in households today. It is available in almost every supermarket across the country. These are really useful in opening cans of soup, or beans, or any other standard-sized can.

Bunker Opener

This classic can opener features two handles with the blade facing downwards to puncture the can and a small key to turn on the handle. To use this type of can opener, you hold the can in place and open the pliers. Place the churchkey on the lid, lift up slightly and close the pliers.

The church key penetrates the can lid, then you turn the key clockwise, holding the can slightly off of the counter. If the can opener slips, you simply turn the opener counter-clockwise and go over that spot again. 

The bunker key can be hard to turn at times and is very fragile in most cases. The metal can bend easily, and these types of keys need to be replaced more often than others. A lot of households find these difficult to use.

Single Wheel

This type of can opener can be really simple to use. You place the top of the wheel on the top of the can, and the magnet attached to the wheel helps hold the can in place.

Turn the Key. As the wheel turns, it cuts through the lid of the can. The magnet adds a layer of grip and helps hold the can in the ideal position to cut the lid off of it.  These keys are used in most households in modern times.

The single-wheel can opener is easy to turn and usually cuts the lid off at the seams. The edge remaining on the can after turning one of these keys is less sharp than most can openers.

The single wheel is really helpful with smaller cans, some of the cans only contain a small number of chilies or some tomato paste.

Side Can Opener

The side can opener has two handles similar to the bunker can opener but utilizes the wheel function of the single-wheel can opener. You would open the pliers and then place the lid of the can on the inside of the can opener’s wheels.

As you open the pliers, a gap is created between the first wheel and the second wheel. You place the can lid up against the wheel closest to the handle inside the gap, then close the pliers. The can opener should be sitting flush with the top of the can.

Turn the key clockwise until it goes around the entire can. As it travels around the can, the wheel grate on the upper side, or outside of the can, will slice the can open between the seams. This type of can opener leaves a smooth edge that is less sharp than the butterfly wheel.

Countertop Opener

These can openers have the largest keys attached to them and are mainly used in commercial settings. They attach to the countertop and have a large handle attached to a bigger church key. You place the can underneath the can opener against the guard. Raise the handle and then push down to puncture the can.

Turn the handle clockwise to open the can. The can opener cuts the top of the lid, similar to the bunker opener. Afterward, you simply pop the top of the lid off and remove it. The countertop key is a large handle that makes it really easy to turn.

Other Objects Used to Open Cans

There are different objects that you can use to open cans without a key.  

Some of the more popular items include:

  1. Chef’s Knife
  2. Pocket Knife
  3. Spoon
  4. Slab of Concrete
  5. Garage tools, i.e., screwdriver, hammer, etc.

You could use anything with a sharp point. Just try not to make jagged edges at the top of the can. If you get jagged edges, you may wind up with metal shavings in your food. This is why stabbing the top of the can is not a recommended method.

Chef’s Knife

Using the bottom part of the chef’s knife, you want to place the edge of the handle against the lip of the can.  Slowly puncture the top of the can with the edge of the knife all the way around the top of the can.  Afterward, you use the knife to open the can. When you need to add something to your dish and are having trouble finding the can opener, this method is a meal saver.

You do want to make sure that you keep a firm grip on the handle of the knife and the can at all times. The grip does not need to be so firm that your hand is not relaxed enough to make smooth motions but not so loose that you slip.

Pocket Knife

A pocket knife has two different ways of opening cans. The traditional swiss army knife® style utility pocket knife usually has a can opener key on the knife. This key has a flat blade, which also doubles as a flat-head screwdriver, along with a hook on the end closest to the handle.

Take the flathead portion of the key and place it on the top of the lid, resting the hook portion under the outside portion of the can lid. Move your wrist in an upward motion to apply downward pressure onto the top of the can. Do this all the way around the can, then use the hook portion to raise the lid away from the sharp edges.

The second method works with a hunting knife as well as a pocket knife. Place the knife blade against the thin portion of the inner lip of the can. The blade should be lined up with the indent of the can standing parallel to the lip of the can.

Grab a rock, or use your hand to lightly tap the top of the knife, puncturing a small hole on the top portion of the can, leaving little to no space between punctures. After you make it around the top, lift the lid with the knife breaking the remaining binds.


This method is useful if the only thing you have is a spoon, and it’s kind of a cool holiday trick. Stand the spoon vertically against the lip of the can, on the inside of the top portion of the can. Begin to slowly move the spoon back and forth by only a few centimeters. Continue to make this motion on the top of the can with the spoon until the top wears thin.

Continue all the way around the top of the can until you make it back to your starting point. You should be able to see the thin layer all the way through the can. Insert the spoon under the lid and pry it open.

Few things to keep in mind with this method:

  1. Go slow
  2. Make sure you are all the way through the lid
  3. Blow off the metal shavings so they don’t get in your food (If you wind up with any)
  4. Don’t tip the can upside down
  5. Keep a firm grip on the spoon
  6. Keep the spoon in a vertical position, do not angle the spoon

The spoon method only works with a spoon. It won’t work with any other utensil or object. The spoon is perfectly angeled to allow wear on the aluminum top of the can.

Concrete Slab

Take the can of food and place it upside down on the concrete slab. You then want to start slowly rubbing the can back and forth on the concrete slab. If you go too fast, then your food will spill out all over the concrete slab.

As you create friction on the can from the concrete slab, the top of the can will weaken enough to let some liquid come out. After you see a little bit of liquid on the concrete slab, flip the can over and then pry it open with your pocket knife.

It is important to remember to go forward and backward with this method. There have been times when you only go forward, pick up the can, bring it back, and start again. The problem with this method is that it only weakens half of the can.

You want to try to keep the concrete out of your food, which is why you only want the slightest bit of moisture to appear on the concrete slab, before turning the can over to pry off the lid.

Garage Tools

This method would be the last resort if you cannot use any of the above methods. This is not the recommended method, but it does work really well.  First, you need to sanitize your instrument, using rubbing alcohol, fire, or even washing them with hot water and dish soap.

You can use the tip of a small flathead screwdriver, holding it at a 45-degree angle. Take a sturdy pencil or other screwdriver and place it across the top of the lid.  Rest the top screwdriver on the screwdriver that is resting on top of the can.

Holding the can and top resting screwdriver in one hand, lightly press on the can with the tip of the 45-degree angled flat-head screwdriver, lift the small screwdriver and move it over, repeating the method. Slowly work your way around the top of the can until you can pry it open and get the food out of the can.

This method is really useful to open a can of soup on a construction site when you can’t find the community can opener, or if you are at a job site with no trailer.

Final Thoughts

Can keys are relatively simple devices to use with a little bit of know-how. There are a number of other alternatives and tools that can be used to accomplish the same goal of opening cans with a little bit of thoughtful action.

Related Questions

How do you fix a can opener? Most can openers stop functioning due to rust and buildup. Simply soak in a vinegar solution and scrub off the rust in order to renew can openers damaged from normal wear and tear.

Are can openers dishwasher safe? Can openers are typically not dishwasher safe since it often uses metals prone to rust and corrosion when exposed to the dishwasher environment.

For more, don’t miss Can You Survive on Canned Food? | Which Types to Store.

Title photo courtesy of Howard Sam [CC BY-SA 3.0 (]