How To Calculate Relative Density

Relative Density Formula:

\[ RD = \frac{\rho_{sub}}{\rho_{ref}} \]

Relative Density (RD):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Relative Density?

Relative Density (also known as specific gravity) is the ratio of the density of a substance to the density of a reference material. It's a dimensionless quantity that indicates whether a substance will float or sink in the reference fluid.

2. How Does the Calculator Work?

The calculator uses the relative density formula:

\[ RD = \frac{\rho_{sub}}{\rho_{ref}} \]

Where:

\( \rho_{sub} \) — Density of the substance (kg/m³)
\( \rho_{ref} \) — Density of the reference material (kg/m³)

Explanation: For liquids and solids, water is typically used as the reference material (1000 kg/m³ at 4°C). For gases, air is commonly used as the reference (1.225 kg/m³ at sea level and 15°C).

3. Importance of Relative Density

Details: Relative density is important in many fields including material science, geology, brewing, and petroleum industry. It helps identify substances, determine purity, and predict buoyancy behavior.

4. Using the Calculator

Tips: Enter both densities in the same units (kg/m³). Both values must be positive numbers. The result is a dimensionless quantity.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between density and relative density?
A: Density is an absolute measurement (mass per unit volume), while relative density is a ratio comparing a substance's density to a reference material's density.

Q2: What reference materials are commonly used?
A: For liquids and solids: water at 4°C (1000 kg/m³). For gases: dry air at standard temperature and pressure (1.225 kg/m³).

Q3: How does temperature affect relative density?
A: Temperature affects both the substance and reference densities. For accurate comparisons, measurements should be made at standardized temperatures.

Q4: What does a relative density less than 1 indicate?
A: A relative density less than 1 means the substance is less dense than the reference material and will float on it.

Q5: Can relative density be greater than 1?
A: Yes, a relative density greater than 1 indicates the substance is denser than the reference material and will sink in it.