A cubic inch is a measurement of volume that is equivalent to measuring a cube of 1 inch (2.5 cm) on each side. Thus, the volume of an object in cubic inches is the same as the calculation of these cubes. There are many ways to calculate the volume of an object in cubic inches, but in the simplest case, with a 3-dimensional rectangular prism (box), the volume is simply length × width × height with all measurements in inches.
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Method 1 of 2: Calculating the Volume of a Square in Cubic Inches
Step 1. Measure the length, width, and height of the object in inches
To calculate the volume of a quadrilateral, all you have to know is the length of its dimensions in inches. You may need to manually measure objects or convert them to inches from other units.
For example, if we want to find the volume of a refrigerator, we need to find its length, width, and height in inches. Suppose our refrigerator has length 50 inches (127.0 cm), wide 25 inches (63.5 cm), and high 20 inches (50.8 cm).
Step 2. Write down the length of your object
The first step to calculating volume with this process is to write down one of your dimensions. You can multiply these dimensions in any order – for our purposes, let's write down the length first.
In our example, we first write 50, because the length of our refrigerator is 50 inches (127.0 cm).
Step 3. Multiply the length by the width of your object
Next, multiply your first dimension by the other dimension. Again, you can multiply your dimensions in any order, but for our purposes, let's multiply the length by the width.
In our example, we will multiply 50 × 25 – the width. 50 × 25 = 1250.
Step 4. Multiply your answer by the height of your object
Finally, multiply the answer you get by multiplying the two dimensions of your object by the remaining dimensions. In our example, it means multiplying the product of the length and width of our object by its height.
In our example, we will multiply 1250 × 20 - the height. 1250 × 20 = 25.000.
Step 5. Give your answer units in cubic inches
You may know that your final answer indicates volume in cubic inches, but others may not. Be sure to use the correct units for your answer, indicating that the volume is in cubic inches.
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Units that can be used include:
- "Cubic Inches"
- "Cubic Inches"
- "Cu. In."
- "Inch3"
Method 2 of 2: Calculating the Volume of Other Objects
Step 1. Calculate the volume of the cube with P3.
A cube is a rectangular prism (square) where each side is the same length. Thus, the volume of a cube can be written as length × width × height = length × length × length = length3. To get your answer in cubic inches, make sure your length measurement is in inches.
Step 2. Calculate the volume of the cylinder with v = tπr2.
A cylinder is an object whose sides are not angled with two circular faces of the same size. The formula v = tπr2 where v = volume, t = height, and r = radius of the cylinder (distance from the center of any surface of the circle to its end), giving the volume of the cylinder. Make sure your t and r measurements are in inches.
Step 3. Calculate the volume of the cone with v = (1/3)tπr2.
A cone is an object whose sides are not angled with a circular base that tapers to a point. The formula v = tπr2/3 where v = volume, t = height, and r = radius of the circle's base, gives the volume of the cone. As above, make sure your t and r measurements are in inches.
Step 4. Calculate the volume of the sphere with v = 4/3πr3.
A sphere is a 3D object that is completely spherical. Equation v = 4/3πr3 where v = volume and r = radius of the sphere (distance from its center to the tip), giving the volume of the sphere. As before, make sure your r measurements are in inches.
Tips
- If you know (and are willing to admit) that your math isn't very good, check your answers using a calculator or someone else. However, make sure you ask someone who knows this for help and that you are pressing the correct button.
- Cubic inches measure volume, how much "something" can fit inside.
- Be sure to use a ruler or tape measure to measure accuracy, especially if you're doing something important, like making something.
