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How to Calculate Density of Water

What is the Density of Water and How to Calculate it?

The density of water is approximately 1 gram per cubic centimetre (g/cm³) or 1000 kilograms per cubic meter (kg/m³) at standard atmospheric pressure and temperature.

To calculate the density of water, you use the formula:

Density (ρ) = Mass (m) / Volume (v)

Measure the mass of the water sample using a scale and the volume using a graduated cylinder or similar tool. Then, plug these values into the formula and perform the division to find the density. Ensure consistent units, such as grams for mass and cubic centimetres for volume, or kilograms for mass and cubic meters for volume, to obtain the density in the appropriate units.

How to Calculate Density of Water: Step-by-Step Guide

Here are three steps that will help us in calculating the density of water:

First Step (Data): It is important to read and understand the question so as to gather all the necessary information.

Second Step (Formula): In this stage, you state the equation that will help you to calculate the density of water, which is Density (ρ) = Mass (m) / Volume (v) or ρ=m/v.

Third Step (Solution): Now, you substitute your formula for the density of water with the data available to you and solve the problem. Ensure to add the si unit to the final result which is in g/mL or gcm-3.

How to Calculate Density of Water
How to Calculate Density of Water


For example, if the mass is 9 g and the volume is 9 mL. We can calculate the density as follows:

ρ = m/v = (9 g) / (9mL) = 1 g/mL

Therefore, the density of water is 1 gram per millilitre

Definition of Density, its Formula, and SI Unit

In order to perfectly understand how to calculate the density of water, we need to understand the definition of density and its formula below:

What is Density?

Density is a fundamental property of matter that represents the amount of mass within a given volume. In simpler terms, it measures how tightly packed the particles are in a substance. The density of water, in particular, refers to the mass of water contained in a specific volume.

Formula for Calculating Density of Water

The formula for calculating density is:

Density = Mass / Volume or (ρ = m/v)

To calculate the density of water, we need to determine the mass and volume of the water sample.

How to Find Density of Water

Measuring Mass

To measure the mass of water, you can use a balance or a scale. Ensure that the balance or scale is calibrated properly before taking any measurements. Place a container on the scale and tare it to zero, then carefully pour the water into the container. Record the mass displayed on the scale.

Measuring Volume

There are several methods to measure the volume of water, depending on the equipment available and the precision required. Here are a few commonly used techniques:

  1. Graduated Cylinder: Use a graduated cylinder to measure the volume of water. Make sure the cylinder is clean and dry. Pour the water into the cylinder, making sure to read the measurement at eye level, where the bottom of the meniscus aligns with the graduation marks. Record the volume.
  2. Pipette or Burette: A pipette or burette can be used to measure precise volumes of water. These instruments are especially useful in laboratory settings where accuracy is crucial. Follow the instructions for proper usage and record the volume accordingly.
  3. Archimedes’ Principle: For irregularly shaped objects, you can use Archimedes’ principle to measure the volume indirectly. Fill a graduated cylinder with a known volume of water, then carefully immerse the object in the cylinder. The change in water level corresponds to the volume of the object. Subtract the initial volume from the final volume to obtain the volume of the object.

Now that we have obtained both the mass and volume of the water sample, we can calculate its density using the formula mentioned earlier. Divide the mass by the volume, and you will have the density of water.

Density = Mass / Volume

The SI unit of density is in kgm-3.

It is important to note that the density of water varies slightly with temperature. The standard density of water is commonly measured at 4 degrees Celsius, where it is most dense. At different temperatures, the density will be slightly higher or lower.

FAQs about Calculating the Density of Water

1. How does the density of water change with temperature?

As the temperature of water changes, its density also changes. Generally, as water gets colder, it becomes denser until it reaches its maximum density at approximately 4 degrees Celsius. As it continues to cool below this point, it expands and becomes less dense. This is due to the unique behavior of water molecules in the liquid state.

2. Can the density of water be greater than 1?

Yes, the density of water can be greater than 1, especially at temperatures above 4 degrees Celsius. For example, when water is heated,

it expands and becomes less dense. At a certain point, it can reach a density lower than that of other substances, causing it to float.

3. How does salinity affect the density of water?

Salinity, which refers to the concentration of dissolved salts in water, can affect its density. When water becomes more saline, such as in the ocean, its density increases. This is because the dissolved salts add mass without significantly increasing the volume.

4. Is the density of water the same everywhere on Earth?

The density of water can vary slightly depending on factors such as temperature, pressure, and salinity. However, these variations are generally small and do not significantly affect everyday calculations. For most practical purposes, the density of water is considered constant.

5. What units are used to measure density?

The most common units used to measure density are grams per cubic centimeter (g/cm³) or kilograms per cubic meter (kg/m³). These units express the mass of a substance in a given volume.

6. Why is knowing the density of water important?

Understanding the density of water is crucial for various applications, including scientific research, engineering projects, and even everyday activities. It allows us to determine buoyancy, calculate fluid pressures, design and operate hydraulic systems, and ensure accurate measurements in laboratory experiments.


In conclusion, knowing how to calculate the density of water is a valuable skill that can be applied in numerous fields. By understanding the concept of density and following the simple formula of dividing mass by volume, you can accurately determine the density of water. Remember to consider factors such as temperature and salinity when necessary. With this knowledge, you can tackle a wide range of scientific and practical challenges with confidence.

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