This bulk modulus calculator helps you compute the bulk elasticity of a material or object based on volume and pressure change in various units. You can discover the formula used and more on the subject below the form.

## How does this bulk modulus calculator work?

This is a useful tool that allows you to calculate the bulk elastic properties of a material through its initial and final volume and the pressure change according to initial and final pressure. Whilst the main function is that of calculating this, the bulk modulus calculator basically allows you to input any four of the equation elements in order to be delivered the fifth one in the result.

There are several measurement units you can use for the volume, from the recommended SI in cube metres (m^{3}) to cube foot (ft^{3}) or liters (l). When adding pressure you are asked to choose from Pa, bar, atm and mmHg.

This is the formula used:

**Bulk modulus = -Vi * (Pf –Pi) / (Vf- Vi)**

where

Vi = initial volume in m^{3}

Vf = final volume in m^{3}

Pi = initial pressure in Pa

Pf = final pressure in Pa

Bm = bulk modulus in Pa

## Example calculation

Let’s take the case of an object with a volume Vi = 5 m^{3 }being reduced to a volume of Vf = 3.4 m^{3 }by a change in pressure of 7 Pa ( Pi = 1.6, Pf = 8.6).

Bulk modulus = -5 * (8.6 –1.6) / (3.4 - 5)

Bulk modulus = 21.875 Pa

## What is bulk modulus?

This is a measure/ ratio that defines how much a material (solid or fluid) will compress under a given amount of change in applied external pressure, therefore it describes the volume elasticity of the material. The reciprocal would be the compressibility of the material. The standard unit is the pascal (Pa) but newton per square metre (N/m^{2}) is often used. Talking about elasticity, it also means that after the pressure is removed, the material regains its volume. Bulk modulus can also be described as the pressure divided by the strain or relative deformation.

What is interesting about this ratio is that it can also describe the amount of energy the Earth’s crust has stored and thus it is used in the study of earthquakes. Did you know that glass has a bulk modulus value of 35 to 55 GPa or that diamonds exceed it with a value of 443 GPa?

28 Apr, 2015