Both extract and all-grain brewers need a good, sturdy kettle for conducting a 60-minute or longer boil. Although you can certainly start out by borrowing a stock pot from the kitchen cupboard, eventually you’ll want to upgrade to a dedicated kettle just for beer. Here are a few things to look for.
Size
Make size your number one consideration because it directly affects what you can brew and how much. Certainly, beginner homebrewers can get away with a pot as small as 3 gallons, but making the best beer possible means boiling as much wort as possible. All-grain homebrewers will need to boil a full volume from the get-go. Plan for the future and buy a kettle that’s at least 1.5 times your batch size. For a 5-gallon batch, that means a kettle of at least 7.5 gallons. Going twice as large gives you even more insurance against a boil over.
Material
Both amateur and professional brewers prefer stainless steel because it’s non-reactive and easy to clean. Unfortunately, it’s also expensive, but since you’ll use this piece of equipment indefinitely, the sticker shock is a little easier to stomach. Aluminum is another good option. It’s lightweight and inexpensive, and aluminum conducts heat much better than stainless. Some consumers are concerned about potential aluminum toxicity, but commercial kitchens use aluminum stockpots every day. Ultimately it’s a matter of personal preference. Neither aluminum nor stainless steel should be cleaned with bleach-based cleaners, as these can degrade both metals.