Size
Size is the first thing to consider when picking out your stock pot. This will likely be the primary determining factor while you shop, so it is usually helpful to decide early in the selection process what size you will need. Residential stock pots come in a variety of sizes that generally range from 6 to 20 quarts. Stock pots larger than 20 quarts are typically only used in commercial applications. A standard, 6 qt. stock pot (included in most basic cookware sets) is typically large enough to prepare most soups, stews, and sauces, but seafood boils and other recipes with large, chunky ingredients will likely require more space to avoid boiling over. If you frequently entertain or cook large batches of soup or stew to freeze for later, a larger stock pot (around 12 quarts) may be a good investment. Obviously, the larger a pot is, the heavier and more unwieldy it will be, especially when it is full of hot liquid. Pots larger than 12 quarts can be cumbersome and will take up a lot of space, making them ideal only for those who regularly cook for large groups.
Shape
In addition to size, shape is also an important factor to keep in mind. Conventionally, stock pots are tall and narrow, although some soup stock pots may be short and wide to allow for easier stirring. Tall pots with narrow bases allow for more consistent heating than wide pots, as the majority of the heat from the burner is “caught” by the base and transferred up into the walls of the pot. Wide pots that are significantly larger than the burner’s effective area will heat less consistently, as the heat from the burner must “waste time” creeping across the bottom of the pot before it can heat the sides. This can cause temperature gradients in your food, which can ultimately lead to inconsistent cooking. While wider, shallower pots can be easier to use in certain situations (i.e. stirring, serving, pouring, etc.) and are great for cooking smaller amounts of soup that don’t rise far up the walls of the pot, the smaller surface area of more narrow pots is ideal for larger recipes that need to be held at a constant temperature for extended periods of time.
Materials
Just as with all cookware, materials are very important when choosing a stock pot. Most stock pots are made of either stainless steel, heavy-duty aluminum, or composites, although there are some pots available with non-stick or enamel coatings. While a non-stick coating may be useful for some specific applications, it is generally not a necessary feature, as most recipes prepared in your stock pot will be liquid-based and will not be at a significant risk of sticking to the cooking surface. Aluminum pots will heat more quickly and consistently than their stainless steel counterparts, but they generally require more care than steel pots, as they tend to be more susceptible to corrosion from acidic ingredients and will require more meticulous cleaning.
Composites
Many cookware manufacturers now offer stock pots that feature embedded cores or base inserts. This composite design combines the best features of multiple materials by surrounding a thermally conductive core of aluminum or copper with an exterior of stainless steel cladding. These cores allow the pot to heat much more consistently than a standard all-steel pot without sacrificing the corrosion resistance and easy to clean nature of stainless steel. Generally, composite pots are available in one of two forms: all-clad or base insert. Pots with only a base insert contain a composite core only in the base of the pan, while all-clad pots feature a full core that runs all the way up the sides of the pot. All-clad pots will naturally be more expensive, but they will ultimately heat more evenly than their base-only counterparts.
Construction
Build quality is another important consideration when selecting your stock pot. The first thing to look for in a quality pot is a thick, heavy base. A heavy base will transfer heat at a more gradual rate, helping to prevent your ingredients from scorching or sticking to the bottom of the pot. Handles are another very important element; a stock pot that you can’t pick up is ultimately not very useful. Look for stock pots with wide handles that are attached securely with rivets or heavy, industrial screws. The handles should also protrude far enough to allow plenty of room for both your hands with potholders. More often than not, your stock pot handles will be warm to the touch, and trying to transport a heavy pot of hot soup with your bare hands is a quick and easy way to either burn yourself or—sometimes worse—spill the soup that you have spent the past several hours preparing.
As a final note in your stock pot selection process, be sure to invest in pots with solid, well-fitting lids. Flat, glass lids are generally preferrable, as they allow you to monitor your food without “peeking.” Flat lids are typically preferrable to domed lids, as they more easily allow you to partially cover the pot for recipes that require slower evaporation. Remember that lids can be purchased separately from your pots, if needed, so if you have found just the right set of pots that come with less than stellar lids, there is always still hope in the cookware aftermarket. Just be sure to bring your pot with you when you go shopping to ensure that the new lids fit properly.