For hanger type variable springs types, a, b, c, d, e, and g, you can utilize the minimum loaded length value (x in the PT&P catalog) and add to that a value equal to your cold load minus the minimum cold load (top red line of the spring chart) divided by the spring rate. For f type variable springs, the loaded length can be set at any height between the minimum and maximum values referenced in the catalog regardless of the initial cold load. The only caveat would be that when dealing with downward movement, one should always ensure that the installed height is large enough to accommodate that downward movement without interfering with the spring housing (or the b dimension as referenced in the catalog).

Various Spring Support Assemblies