How do you find the surface area of a rectangular prism?

To calculate the surface area of a rectangular prism, calculate and add together the surface areas of all its faces. Performing this calculation takes just a few minutes.

1. Calculate the width of one face

   Measure the lengths of any two edges that come together at one corner. Multiply them together to get the surface area of the face that is common to those two edges.

2. Calculate the width of a second face sharing a common edge with the first

   Measure the length of the third edge coming from that corner, and multiply it by either of the previously measured edges. The answer is the surface area of the face that is common to those two edges.

3. Calculate the width of a third face sharing a common corner with the first two

   Multiply the length of the edge measured in the previous step by the length of the edge not used in the previous step. That's the surface area of the face that is common to those two edges.

4. Add the areas of those three faces

   Calculate the sum the surface areas of those three faces.

5. Multiply the total area of those three faces by two

   Since each of those three faces has a corresponding opposite face of equal area, double the sum to arrive at the final surface area.