2x3

The 2x3 is the smallest of the common index card sizes, measuring just 2 inches wide by 3 inches high. With a total surface area of 6 square inches, it provides limited but useful space for quick notes, very short reminders, and other situations where minimal writing real estate is required. Sometimes referred to as the pocket index card, this petite size was popular for library card catalogs in the late 1800s when just a small amount of information needed to be recorded. The highly compact 2x3 can also be handy for simple flashcards, recipe ingredient lists, and anywhere portability is the priority over writing capacity. Its small dimensions allow it to fit in virtually any pocket or wallet. While not suitable for extensive writing, the versatile 2x3 index card serves an important niche role when space is extremely constrained but notes still need to be captured. It fills the need for true portability and brevity.