Extension Spring Force Formula and Calculator

Spring Design Menu

This calculator will determine the spring rate related to an extension spring from basic geometry and material data input. Default units are shown in inches, etc however SI (metric) can be used.

Spring Force Formula

This calculator will calculate any of the values remaining by changing one of the variables then selecting the "calculate: button for the selected variable.

Equation: TF = IT + (D x k)


TF = Total Force exerted on spring

D = Distance spring is deflected

IT= Initial tension force on spring

k = Spring constant determined by experiment or calculation

(This calculator requires a java - enabled browser)

Open Extension Spring Force Formula and Calculator

About Extension Spring Design:

Most extension springs are wound with an initial tension. This tension is the force that holds the spring coils wound together. The spring rate tends to be constant over the central 60 percent of the deflection range. When designing for a particular spring, design for critical loads and rates to be within the central 60% deflection and load range. Standard and custom springs are available.  Exceeding manufactures maximum deflection almost always reduces usable spring life cycles.