Blood pressure in the capillaries is expected to be lower than in arterioles or arteries. That is because pressure is a function of force per unit area or P=F/A. The larger the surface area, the lesser the pressure. Capillaries have small radii but have the largest surface area in the network of blood vessels. Their velocity is lower as well as is their pressure. Arteries have a larger vessel diameter, which means resistance is low and velocity is faster, resulting in a higher pressure. Even though arteries are much larger vessels, their surface area is much smaller than capillaries which inundate the tissues of the body.