# Hooke’s Law Calculator (Spring Force)

URL: https://speedycalculator.com/calculators/physics/hookes-law/
Last updated: 2026-10-25

> The Hooke’s law calculator finds the force of a spring from its stiffness and extension, F = kx, and the elastic potential energy stored, ½kx².

## Inputs

- Spring constant (k) (N/m)
- Extension (m, cm, mm, km, in, ft, yd, mi)

## Results

- Spring force
- Stored energy

## Formula

```
F = k x
E = ½ k x²
```

## Explanation

Within its elastic limit, a spring stretches in proportion to the force applied.

### How to use the Hooke’s Law Calculator

- **Spring constant (k)**
- **Extension**
- Want to work backwards? Type a value into **Spring force** and **Extension** is calculated for you.

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Multiply the spring constant by the extension or compression.

### Inputs explained

FieldWhat to enterSpring constant (k)In N/mExtensionUnits: m, cm, mm, km, in, ft …

### What each result means

- **Spring force** = [Spring constant (k)] × [Extension]
- **Stored energy** = 0.5 × [Spring constant (k)] × [Extension]^2

### Example values

How the main result changes when **Extension** changes and everything else stays at the example values above:

Extension (m)Spring force (N)0.05250.07537.50.1500.12562.50.15750.2100

## Worked example

Inputs — Spring constant (k): 500 N/m; Extension: 0.1 m.

Results — **Spring force = 50 N**; Stored energy = 2.5 J.

## FAQ

**What is the elastic limit?**
The point beyond which the spring is permanently deformed.

**How do I find k?**
Hang a known weight and divide the force by the extension.

**What formula does the Hooke’s Law Calculator use?**
F = k x.

**Can I work backwards from the result?**
Yes. Type the result you want into Spring force and the calculator finds the matching extension.