# Bulk Modulus Calculator

URL: https://speedycalculator.com/calculators/physics/bulk-modulus/
Last updated: 2026-10-30

> The bulk modulus calculator finds a material's bulk modulus – its resistance to uniform compression – from the pressure change and the resulting change in volume.

## Inputs

- Pressure change ΔP (MPa, kPa, bar, atm, psi, GPa)
- Initial volume V₀ (L, mL, m³, US gal, ft³)
- Volume decrease ΔV (mL, L, cm³, m³)

## Results

- Volumetric strain ΔV/V₀
- Bulk modulus K
- Compressibility β

## Formula

```
K = −ΔP / (ΔV/V₀),  compressibility β = 1/K
```

## Explanation

Squeeze a material from all sides and its volume shrinks a little. The bulk modulus tells you how much pressure is needed: water's is about 2.2 GPa, steel's 160 GPa. It also sets the speed of sound in fluids.

### How to use the Bulk Modulus Calculator

- **Pressure change ΔP**
- **Initial volume V₀**
- **Volume decrease ΔV**

Results update as you type, every field has its own unit menu, and everything is calculated in your browser.

### How it works

Enter the pressure increase, the initial volume and the decrease in volume.

### Inputs explained

FieldWhat to enterPressure change ΔPUnits: MPa, kPa, bar, atm, psi, GPaInitial volume V₀Units: L, mL, m³, US gal, ft³Volume decrease ΔVUnits: mL, L, cm³, m³

### What each result means

- **Volumetric strain ΔV/V₀** = [Volume decrease ΔV]÷[Initial volume V₀]
- **Bulk modulus K** = [Pressure change ΔP]÷([Volume decrease ΔV]÷[Initial volume V₀])÷1e9
- **Compressibility β** = 1÷([Bulk modulus K]×1e9)

### Example values

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

Pressure change ΔP (MPa)Bulk modulus K (GPa)51.11117.51.6667102.222212.52.7778153.3333204.4444

## Worked example

Inputs — Pressure change ΔP: 10 MPa; Initial volume V₀: 1 L; Volume decrease ΔV: 4.5 mL.

Results — Volumetric strain ΔV/V₀ = 0.0045; **Bulk modulus K = 2.22222 GPa**; Compressibility β = 4.5000e-10 Pa⁻¹.

## Key terms

- **Volumetric strain**: Relative change in volume.

## FAQ

**What is the bulk modulus of water?**
About 2.2 GPa.

**Why is the sign negative in the formula?**
Pressure increases make the volume decrease.

**What is compressibility?**
The reciprocal of the bulk modulus.

**How does bulk modulus relate to sound speed?**
In a fluid, c = √(K/ρ).


## Sources

- [MIT OpenCourseWare – Mechanics of Materials](https://ocw.mit.edu/courses/2-001-mechanics-materials-i-fall-2006/)
- [The Engineering ToolBox](https://www.engineeringtoolbox.com/)