# Density Calculator

Density describes the **relationship between mass and volume**: learn how to calculate and discover the values of some interesting materials with our density calculator.

Here you will learn:

**What is density**?**How to calculate density**: formula and explanation?- Example of density: how to find the
**extremes**of this quantity in the Universe. - Why do objects float?

## What is density?

Density is an **intensive property of matter**, which means that its value doesn't depend on the **size** of the system. Density measures the **mass per unit of volume**. Notice how both mass and volume are extensive properties: calculating their ratio excludes the system's physical characteristics from the definition of density.

Density is, roughly speaking, a measure of how **packed** atoms (or subatomic particles) are. The bigger the space between them, the lower the density. This is why, intuitively, gases are far less dense than solid objects.

## How to calculate density

To calculate density, you must know:

- The mass of the object, $m$; and
- The volume of the object, $V$.

The density formula is then:

Choose the appropriate **measurement units**: density is most often calculated in **kilograms per cubic meter**, but there may be situations where other units may be more convenient (**grams per cubic centimeter** comes to mind).

## Density examples

The most commonly quoted example of density is **water**. A cubic meter of water, at $4\ \degree\text{C}$ has a mass of exactly $1,000\ \text{kg}$. This is no coincidence: the kilogram's definition used a reference to water: in 1795, the weight of a liter of water was decided to correspond to a kilogram.

The densest material that can exist naturally on Earth is **osmium**, the element number 76. In its metallic state, at room temperature, a cubic meter of osmium weighs a staggering $22,750\ \text{kg}$!

Moving away from our home planet, we find extremes examples of density:

- The density of
**intergalactic medium**: this mostly empty space between galaxies contains approximately one atom per square meter. Assuming this atom to be**hydrogen**, the most common in the Universe, the density of the medium would be $1.67\cdot10^{-27}\ \text{kg}/\text{m}^3$. - Staying closer to the Earth, we can consider the
**interstellar medium**, which is**eight orders of magnitude**denser than the emptiness between galaxies. Said so, with a density of $2\cdot10^{-19}\ \text{kg}/\text{m}^3$, it's still mostly emptiness. - The density of the core of a
**neutron star**lies at the other end of the spectrum. Those stellar remains contain the core of a sun compressed in the size of a city: with a diameter of a dozen of kilometers or so and masses comparable to the one of the Sun, they pack an impressive density of $4.8\cdot10^{17}\ \text{kg}/\text{m}^3$. - Denser?
**Black holes**can be even**denser**, and the bigger, the better. However, they don't stop at all, reaching the point in which they**break physics**and create the**singularity**, a point in space with**infinite density**.

## Why do objects float?

Our density calculator can tell you if a given material floats or sinks. In the bottom part of the calculator, select "non-metals" and then "wood (typical)". Wood's density is, on average, $700\ \text{kg}$ per cubic meter, which tells us that it easily floats.

Now, select "metals", "iron", and answer the question, "will it float?" With $7,870\ \text{kg}$ per cubic meter, iron sinks quickly. So how do boats float?

Let's ask Archimedes. The key of floating is in the **displacement** of water. If a body displaces a volume of water with mass greater than the one of the body itself, then the body will float: we talked in detail about this at our buoyancy calculator. Ships are mostly made of air, which greatly reduces their weight: hence, they float.

## How to use our density calculator

Our density calculator will help you with two different questions:

- How to find the density of a material (with the density formula)? Input the mass and volume of the object, and choose the desired measurement unit for the density.
- Will a material float in water (at $4\ \degree\text{C}$? Choose a material from two lists of presets (first a general type and then a more specific material), and discover their density — and if they float.

Try our density converter to focus more on the conversion between the measurement units of density rather than on the calculation themselves.

*Nope, it's gonna sink.*