Whether something is small or large is a relative term; therefore, it is not possible to say in terms of absolutes whether 5 inches is small or large. For perspective, 5 inches is approximately the length of an iPhone 5.
Five inches would be small for larger measurements, such as the length of a car or a canoe, but 5 inches is quite large compared to many things, such as the diameter of a coin. For example, a penny has a diameter of 0.75 inches, and a quarter has a diameter of 0.96 inches. Therefore, 5 inches is between six and seven times the diameter of a penny and just over five times the diameter of a quarter.