Hookes Law Spring Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
Enter Values
How to use this calculator
- Enter any two of: force F (N), spring rate k (N/mm), deflection x (mm).
- Leave the third blank — the calculator solves for it.
- Read all three values back.
How it works
The Hooke's Law Spring Calculator relates the force on a linear spring to how far it moves using F = k·x.
k is the spring rate (stiffness) — the force needed per millimetre of deflection. Given any two of force, rate and deflection, the third follows. It holds while the spring stays within its elastic range.
Worked example
k = 20 N/mm, x = 5 mm. F = 20 × 5 = 100 N. The same spring pushed to 7 mm would give 140 N.
Frequently asked questions
What is spring rate?
Spring rate (k) is the stiffness — the force required to compress or extend the spring by one millimetre. A higher rate means a stiffer spring.
Does this work for any spring?
It works for linear springs within their elastic range. Near full compression, or for progressive/non-linear springs, the relationship is no longer a straight line.
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.