Surface Area of Prisms
Sum the areas of all faces.
Key idea
Sum the areas of all faces.
In depth
Surface area is the total area of all faces. Unfold the prism into a net, find the area of each face, and add. For a prism, SA = 2 × base area + perimeter of base × height.
Worked example
A box 2 × 3 × 4: 2(6 + 8 + 12) = 52.
Real-world uses
- Working out the wrapping paper or paint needed for a box
- Estimating the cost of a container
Common mistake
Forgetting one of the faces or counting hidden ones twice.
How to learn this
- Read the key idea and say it in your own words.
- Work through the worked example, then try a similar problem.
- Use the interactive lesson’s visual and mini-quiz to check the pattern.
Frequently asked questions
What is Surface Area of Prisms?
Sum the areas of all faces. It is a topic at the intermediate level in Geometry.
Where is Surface Area of Prisms used in real life?
Real-world examples: Working out the wrapping paper or paint needed for a box; Estimating the cost of a container.
What should I learn before Surface Area of Prisms?
Make sure you are comfortable with Volume of Prisms and Cylinders, the previous topic in Geometry.
What is a common mistake with Surface Area of Prisms?
Forgetting one of the faces or counting hidden ones twice.
How can I practise Surface Area of Prisms?
Open the interactive lesson, play with the visual, then answer the three-question mini-quiz. Getting two right marks the topic complete.
What comes after Surface Area of Prisms?
Move on to Cylinders: Surface Area next.
Related intermediate topics in Geometry
- Vertical Angles – Opposite angles formed by intersecting lines are equal.
- Parallel Lines and Transversals – Corresponding and alternate interior angles are equal.
- Exterior Angle Theorem – An exterior angle equals the sum of the two remote interior angles.
- Triangle Inequality – Any two sides sum to more than the third.
- Congruent Triangles – Same shape and size: SSS, SAS, ASA, AAS, HL.
- Similar Triangles – Same shape, proportional sides: AA, SAS~, SSS~.