Density Calculator (p = m/V)
Solve for density, mass, or volume. Enter any two known values and calculate the third instantly.
Common Material Densities Reference
Density reference values help you verify calculations and understand the relative mass per unit volume of familiar materials.
| Material | Density (g/cm³) | Density (kg/m³) | Density (lb/ft³) |
|---|---|---|---|
| Water (4°C) | 1.000 | 1000 | 62.43 |
| Ice | 0.917 | 917 | 57.24 |
| Air (20°C, 1 atm) | 0.001204 | 1.204 | 0.0752 |
| Aluminum | 2.70 | 2700 | 168.6 |
| Iron | 7.87 | 7870 | 491.2 |
| Copper | 8.96 | 8960 | 559.4 |
| Gold | 19.32 | 19320 | 1206 |
| Lead | 11.34 | 11340 | 707.9 |
| Oak Wood | 0.77 | 770 | 48.07 |
| Concrete | 2.30 | 2300 | 143.6 |
| Ethanol | 0.789 | 789 | 49.27 |
| Mercury | 13.53 | 13530 | 845.0 |
The Density Formula Explained
The density formula p = m/V defines density as the amount of mass contained in a unit of volume. It is one of the most fundamental relationships in physics and chemistry, used across engineering, materials science, cooking, geology, and medicine.
m = p × V (mass = density × volume)
V = m / p (volume = mass ÷ density)
This calculator accepts any two of the three variables and solves for the third, making it equally useful whether you know mass and volume, density and volume, or density and mass.
How to Use This Density Calculator
Select which variable you want to solve for using the radio buttons at the top. The selected field will be highlighted and locked. Enter your known values in the remaining two fields, choose the appropriate units for each, and click Calculate. The result appears with the full formula substituted with your numbers.
Choosing the Right Units
Metric units such as g/cm³ and kg/m³ are standard in science. For practical applications in the United States, lb/ft³ and lb/in³ are common. This calculator automatically converts all inputs to a common base (g/cm³) before computing, then converts the result back to your chosen output unit, so you can mix and match freely.
What Does Density Tell You?
Density tells you how tightly packed the matter inside an object is. A high density means a lot of mass is squeezed into a small volume; a low density means the opposite. Gold, one of the densest common metals, has a density of 19.32 g/cm³, while balsa wood sits around 0.12 g/cm³, roughly 160 times less dense.
Density explains why objects float or sink: an object less dense than the surrounding fluid will float, and an object more dense will sink. Water has a density of 1.00 g/cm³ at 4°C, which is why it serves as the universal reference point for specific gravity.
Density in Chemistry and Physics
In chemistry, density helps identify unknown substances by comparing measured density to known reference values. In physics, density is central to fluid dynamics, buoyancy (Archimedes’ principle), atmospheric pressure calculations, and acoustic wave behavior. Engineers use density when designing structures to ensure materials can bear required loads without excessive weight.
Significant Figures in Density Problems
Significant figures in density calculations reflect measurement precision. If your scale reads mass to three significant figures and your volume measurement also has three, your final answer should be reported to three significant figures. This calculator lets you choose from auto (full precision) to 3 through 9 significant figures for scientifically appropriate reporting.
Density Conversion Between Unit Systems
Density conversion between SI and US customary units requires knowing the conversion factors for both mass and volume. For example, 1 lb/ft³ equals 16.018 kg/m³. See our dedicated Density Conversion Calculator for a full table of all unit conversions.