Calculate spring pressure and force from spring rate, compression, and contact area or diameter, with results in Pa, psi, N, and lbf.

Area the spring force presses on, such as a wastegate diaphragm or valve face, not the spring wire.

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Spring Pressure Formula

For a linear spring with no preload, the following formula gives average pressure over the loaded contact area. It does not calculate peak contact stress or spring-wire stress.

Pspring = K ร— X / A
  • Where Pspring is the Spring Pressure (Pa)
  • K is the spring rate (N/m) 
  • X is the compression (m) 
  • A is the loaded contact area (m2), not the spring wire cross-section 

Multiply spring rate by compression from the unloaded length to get force, then divide by loaded contact area. For a circular contact, A = ฯ€dยฒ/4 using its contact diameter. The calculator also solves for rate, compression or area; selected units are converted before calculation.

How to Calculate Spring Pressure?

The following example problems outline how to calculate the Spring Pressure.

Example Problem #1

  1. First, determine the spring rate (N/m). In this example, the spring rate (N/m) is given as 100.
  2. Next, determine the compression (m). For this problem, the compression (m) is given as  .5.
  3. Next, determine the loaded contact area (m2). In this case, the loaded contact area (m2) is found to be .75.
  4. Finally, calculate the Spring Pressure using the formula above: 

Pspring = K * X / A

Inserting the values from above and solving yields: 

Pspring = 100 * .5 / .75 = 66.67 (Pa)

Example Problem #2

Using the same method as above, determine the variables required by the equation. For this example problem, these are provided as:

spring rate (N/m) = 500

compression (m) = 3

loaded contact area (m2) = 5

Entering these given values yields: 

Pspring = 500 * 3 / 5 = 300 (Pa)