How is the right and left hand wound spring distinguished?

The direction of the spring wind can be easily determined by holding it in hand. The fingers should be placed on the outside of the body, and your thumb should point upwards. If the last coil of the spring points in the same direction of your fingers, then you are looking at the right handed spring. If it turns away from your fingers, then you are looking at the left handed spring.

Many times, the wind direction becomes an important consideration. This is especially when you are working with torsion springs, where coils come closer during the deflection. The ends of compression or extension springs may also stick up with a mating machined part. Thus, the wind of the spring must match direction of spring threads.