Helical Spring Index Calculator

Calculate Your Spring Index (C)

Please enter the mean coil diameter.
Please enter the wire diameter.

Calculation Result:

Helical Spring Index (C):

Quickly calculate the helical spring index (C), a crucial parameter in spring design and analysis. This online tool helps engineers and students determine the ratio of mean coil diameter to wire diameter for optimal spring performance, stress analysis, and manufacturability.

Formula:

The Helical Spring Index (C) is a dimensionless ratio calculated using the formula:

C = D / d

  • C = Helical Spring Index
  • D = Mean Coil Diameter (e.g., in mm or inches)
  • d = Wire Diameter (must be in the same units as D)

A higher index typically means a more flexible spring, while a lower index indicates a stiffer spring. The optimal range for C is generally between 4 and 12.

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