How many sink holes that you need all depends on what faucets and appliances you intend to have installed in your kitchen. While there are kitchen faucets that only require 1 hole, generally a kitchen faucet with a plate at its base requires 3 holes. However, the more features that you want to have attached to your sink, the more sink holes you will need. If you are buying a new kitchen sink, the best thing to do is sit down and plan out what kind of conveniences you would like to enjoy in the kitchen.
For example, if you want a sprayer for your dishes, you will need an extra hole for it. Then, if you have a dishwasher you will need a hole for that as well. This is because 1 hole is required for the air gap. Accessories like a hot water dispenser or a water filter outlet will also require a hole for each appliance. As well, what sink couldn't use a soap dispenser? That would be one more hole. As you can see, if you are planning on installing a new sink; these days, there are many more options than just installing a faucet that puts out hot and cold water.
Our suggestion is this: decide which faucets and appliances you would like and then discuss them with your local plumber. He is the best person to advise you about what kind of kitchen sinks are available for all of the features that will make sure that your kitchen sink is perfect for all of your needs. A licensed plumber can also install your sink properly and make sure that it meets with the local plumbing codes. As opposed to doing it all yourself, a licensed plumber will ensure that your sink will last for years to come and also provide you with a sink that will add value to your home.