Arm span or reach (sometimes referred to as wingspan) is the physical measurement of the length from one end of an individual's arms (measured at the fingertips) to the other when raised parallel to the ground at shoulder height at a 90º angle. The average reach correlates to the person's height. Age and sex have to be taken into account to best predict height from arm span.
An above-average reach is advantageous in sports such as basketball, boxing, discus throw, fencing, and swimming. For instance, boxer Sonny Liston had an 213 cm (84 in) reach despite being only 184 cm (72.5 in) in height. This unusually long reach allowed him to hit opposing boxers from relatively safe distances where they could not reach him.
Because any decrease in height will cause an increase in the ratio of arm-span to height, a large span-to-height ratio may sometimes be an indicator of a health problem that has caused a decrease in height. Large arm-span is also mechanically disadvantageous on the bench press, as it forces the lifter through a wider range of motion.
To measure the arm span, the person must be standing up against the wall with their arms extended sideways at a ninety-degree angle. A person with a length measuring tool (usually a tape measure) will measure from one end of the tip of the middle finger to the other. This method can be easily done at home and it is not necessary to see a physician, unless for a checkup.