In basic physics laboratories, springs are normally used to determine both spring constants and the Earth's gravitational acceleration. Students generally do not notice that the spring constant is not a universal constant, but depends on the spring parameters. This paper shows and verifies that the spring constant in the linear range is inversely proportional to the number of windings and to the cube of its effective spring diameter. The linear range is taken in the region of force greater than a minimum value which is referred to as the initial force F[subscript 0]. The relationship between initial force F[subscript 0] and spring constant is still unclear. Shear modulus and Young's modulus of the spring material can then be calculated using the spring constant. (Contains 1 table and 4 figures.)