The feel of any ball is dependent on proper inflation.  Mikasa offers a digital pressure gauge ($35) usable on any ball with a standard inflation needle.  The gauge displays pressure in a variety of measurements.

Many coaches, referees and players judge the pressure of a ball by the squeeze method.  Occasionally a player will juggle the ball or bounce it, but these are very imprecise tests.  To test the exactness of the human scale, we started with 10 balls from a variety of manufactures.  Each ball was judged by the players as correctly inflated.  When we tested those ball with the Digi-Gage, we found that all were underinflated.  The average difference was 2 psi.  Players can learn to judge proper inflation, but they must become accustomed to a properly inflated ball first.

A pressure gauge is the only way to accurately measure a balls inflation.  The Mikasa Digi-Gage offers four measurements including Pounds per Square Inch (psi); Atmospheric Pressure (bar), Kilogram Force per Square Centimeter (kgf/cm2), and Kilopascals (kPa).  PSI and bar are the most common measurements in the US.  Most of the balls we test show the manufacturer's suggested pressure range in psi.  Occasionally, they will also have the bar measurement printed on the ball as well.  Some training balls do not have a suggested pressure range.