How to Calculate Density

Density Calculator

Grams (g) Kilograms (kg) Pounds (lb)

cm³ m³ Milliliters (mL) ft³

function calculateDensity() { var mass = parseFloat(document.getElementById('mass').value); var volume = parseFloat(document.getElementById('volume').value); var massUnit = document.getElementById('massUnit').value; var volumeUnit = document.getElementById('volumeUnit').value; var resultArea = document.getElementById('resultArea'); var output = document.getElementById('densityOutput'); var formula = document.getElementById('densityFormula'); if (isNaN(mass) || isNaN(volume) || volume <= 0) { alert("Please enter valid positive numbers for both mass and volume."); return; } var density = mass / volume; var densityRounded = Math.round(density * 10000) / 10000; resultArea.style.display = 'block'; resultArea.style.backgroundColor = '#e8f4fd'; var unitString = massUnit + "/" + volumeUnit; if (volumeUnit === "cm3") unitString = massUnit + "/cm³"; if (volumeUnit === "m3") unitString = massUnit + "/m³"; if (volumeUnit === "ft3") unitString = massUnit + "/ft³"; output.innerHTML = "Density (ρ) = " + densityRounded + " " + unitString; formula.innerHTML = "Calculation: " + mass + " (" + massUnit + ") ÷ " + volume + " (" + volumeUnit + ")"; }

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Density is a fundamental physical property of matter that describes how much mass is packed into a specific volume. Whether you are a student, engineer, or hobbyist, understanding how to calculate density is crucial for identifying substances and predicting how objects will interact in fluids (such as floating or sinking).

The Density Formula

The standard formula for density is represented by the Greek letter rho (ρ):

Density (ρ) = Mass (m) / Volume (V)

Step-by-Step Instructions

1. Measure the Mass: Use a scale or balance to find out how heavy the object is. In the metric system, this is usually measured in grams (g) or kilograms (kg).
2. Determine the Volume:
   • For regular solids (like cubes or spheres), use geometry formulas (e.g., Length × Width × Height).
   • For irregular solids, use the water displacement method (measuring how much water level rises in a graduated cylinder when the object is submerged).
   • For liquids, simply use a measuring cup or graduated cylinder.
3. Perform the Division: Divide the mass value by the volume value using the formula above.

Real-World Example

Imagine you have a metal block with a mass of 200 grams. You measure its dimensions and find its volume is 25 cubic centimeters (cm³).

Using the formula: 200g / 25cm³ = 8 g/cm³.

Since the density of water is approximately 1.0 g/cm³, this metal block will sink because its density is higher than that of water.

Common Densities Table

Substance	Density (g/cm³)
Pure Water	1.00
Aluminum	2.70
Iron	7.87
Gold	19.32
Ice	0.92

Frequently Asked Questions

Q: Why does density matter?
A: It helps determine if an object will float or sink. It is also used to identify unknown materials since every pure substance has a unique density.

Q: Does temperature affect density?
A: Yes. For most substances, as temperature increases, volume increases (thermal expansion), which causes density to decrease. Water is a unique exception between 0°C and 4°C.