This stiffness calculator finds the stiffness k of a spring or structural member from the applied force and the resulting deflection. Enter both values above.
Formula
Stiffness k = Force ÷ Deflection
Example
Force 500 N, deflection 0.01 m: k = 500 ÷ 0.01 = 50,000 N/m.
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Frequently Asked Questions
How do I calculate stiffness?
Divide the applied force by the deflection it causes: k = F / x. The result is in newtons per meter.
What is a high stiffness?
A high k means the member barely deflects under load; a low k means it is flexible.
Is stiffness the same as strength?
No. Stiffness resists deflection; strength resists failure. A material can be stiff but brittle.