How to Convert Dry Weight to Volume

Both density and volume determine weight.

When you need to determine the volume of an item, certain shapes make the calculations easier. For example, cubes or spheres have regular geometric formulas that can be used to quickly calculate their volume from simple measurements of length or diameter. Irregularly shaped objects, however, present more of a challenge because they do not have formulas to calculate volume. Instead, you can weigh the object and convert the weight to volume by using the density of the item. Density measures weight per unit of volume, so it provides an easy method of calculating volume for irregular solids as well as liquids and gases.

Things You'll Need

• Weight
• Density
• Paper
• Pen or pencil
• Calculator (optional)

Instructions

1. Write down the weight and the density of the item you want to measure. Include the units of measurement, such as ounces, pounds or kilograms for weight, and pounds per square inch, grams per square centimeter or kilograms per liter for density.

2. Check that the weight of the item whose volume you want to calculate is stated in the same units as the density. For example, if the density is kilograms per square meter, then the weight to be converted must be in kilograms.

3. Divide the weight by the density. Even if you are using a calculator, do the calculations twice to reduce the likelihood of human error.

4. Cancel the weight unit and the unit from the top of the density unit. For example, if you are dividing "pounds" by "pounds per square foot," you have to cancel "pounds" from both measurements.

5. Write the volume with the remaining unit. Don't forget that the answer isn't complete unless you include the unit of measurement.

Tips & Warnings

• For a cube or rectangular box, multiply the length times the width times the height to find the volume in square units. You do not need to weigh the box. For a sphere, cube the radius, (or calculate the radius to the third power). Multiply by 4, and then multiply by pi (3.14). Divide by 3 to gain the volume of the sphere in square units. You will not need to weigh the sphere. Liters are generally used to measure the volume of liquids and gases, while square units are used for solids.

• Don't confuse volume units with length units. Although square inches use inches as a basis, they are measurements of altogether different aspects.

Resources

• Densities of Common Substances