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How to Calculate Relative Density Percentage?

Relative density percentage, also known as specific gravity, is a measurement that compares the density of a substance to the density of a reference substance, usually water. It is a useful parameter in various scientific and industrial applications, such as determining the purity of a substance or assessing its suitability for specific purposes. In this article, we will guide you through the steps to calculate relative density percentage.

Step 1: Understand the Concept of Relative Density

Before diving into the calculations, it is essential to grasp the concept of relative density. As mentioned earlier, it is the ratio of the density of a substance to the density of a reference substance. The reference substance is typically water, which has a density of 1 gram per cubic centimeter (g/cm³) or 1000 kilograms per cubic meter (kg/m³).

Step 2: Gather the Required Information

To calculate the relative density percentage, you need to know the mass (weight) and volume of the substance you are testing. Make sure you have precise measurements for both. The mass is usually measured in grams (g) or kilograms (kg), while the volume can be in cubic centimeters (cm³) or liters (L).

Step 3: Calculate the Density of the Substance

The density of a substance is calculated by dividing its mass by its volume. The formula is as follows:

Density = Mass / Volume

For example, if the mass of the substance is 50 grams (g) and the volume is 25 cubic centimeters (cm³), the density would be:

Density = 50 g / 25 cm³ = 2 g/cm³

Step 4: Calculate the Relative Density Percentage

Once you have determined the density of the substance, you can calculate the relative density percentage by dividing it by the density of the reference substance (water) and multiplying by 100. The formula is as follows:

Relative Density Percentage = (Density of Substance / Density of Water) x 100

Using the previous example, if the density of the substance is 2 g/cm³, the relative density percentage would be:

Relative Density Percentage = (2 g/cm³ / 1 g/cm³) x 100 = 200%

Step 5: Interpret the Results

The relative density percentage represents how many times denser or lighter the substance is compared to water. A value greater than 100% indicates that the substance is denser than water, while a value less than 100% suggests that the substance is lighter than water.

It is important to note that relative density is a dimensionless quantity, meaning it has no units. The percentage symbol (%) is used to express the value as a ratio multiplied by 100.


Calculating relative density percentage is a straightforward process that involves determining the density of a substance and comparing it to the density of water. By following the steps outlined in this article, you can accurately calculate the relative density percentage and gain valuable insights into the characteristics of the substance under investigation.

Remember to use precise measurements and apply the appropriate formulas to obtain accurate results. Whether you are conducting scientific experiments, analyzing materials, or evaluating the quality of a product, understanding relative density can provide valuable information for your endeavors.

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