When buying paint for use around your home, you may notice exterior paint cans displaying a base number for the paint, such as "Base 3." This number gives you information about the ingredients in the paint.
The base number included on a paint can refers to the different base paints that can be used to start the process of mixing your desired color. The base is the foundation that other colors are added to.
Base numbers refer to the paint used to tint, or change the color of, your paint. Typically, the higher the base number, the darker the color of tinting paint.
If you are just buying paint and not mixing it yourself, the base number is not as important as the finished color of the mixed paint. Keep in mind, however, that paints with a darker tint will fade faster, especially when used in exterior settings.