Arm span

Arm span, also called reach, is the distance from one fingertip to the other when a person's arms are stretched out to the sides. This distance is often very close to a person's height. It can be useful when someone cannot stand up straight to measure their height, like when they have back or leg problems, such as scoliosis or osteoporosis.

Arm span helps health experts guess a person's height when traditional ways are not possible. Other ways to measure height include looking at knee length or measuring someone lying down.

Sometimes, if the arm span is much larger than the person's height, it might suggest health issues, such as changes in the spine from aging or certain spinal conditions.

Arm span in sports

Having longer arms can be very helpful in many sports. For example, in basketball, tennis, and swimming, a longer reach helps athletes do better. Famous boxers and fighters, like Sonny Liston and Jon Jones, used their long arms to stay away from their opponents while they attacked. However, having very long arms can make some activities, like weightlifting, a bit harder.

Procedure

The easiest way to measure someone’s arm span is by using what’s called the demi-span. You can use a tape measure to find the distance from the center of the person’s chest, near the breastbone, to the tip of their middle finger when their arm is stretched out to the side. Then, you simply double that number to get the full arm span. This method is helpful because measuring from fingertip to fingertip usually needs help from another person or markings on a wall.

In situations where a person can’t easily stand up, such as when they are lying in bed, their arm span can be used to guess their height. On average, a person’s arm span is very close to their height, so measuring the arm span can give a good idea of how tall they are.