Surface Area of a Rectangular Prism Formula
Geometry Formulas: Area, Volume, Perimeter
What is the formula for the surface area of a rectangular prism?
Answer
Surface area of a rectangular prism
S = 2 · (a·b + a·h + b·h)
Here a is the side (or base), b is the second side, h is the height, perpendicular to the base. The result comes out in square units.
Where the formula comes from
S = 2 · (a·b + a·h + b·h)
Six faces in three matching pairs: top and bottom are a·b, front and back are a·h, the two sides are b·h. Add one of each and double.
Worked examples
Let a = 5, b = 4, h = 3. Then the surface area of a rectangular prism = 94 square units.
Let a = 2.5, b = 6, h = 1.2. Then the surface area of a rectangular prism = 50.4 square units.
The common mistake
Doubling only the first pair. The 2 multiplies the whole bracket, not just a·b — every one of the three pairs has two members.
Other quantities: Rectangular prism
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- Square Meters to Square Feet (Sq M to Sq Ft) - Convert Square Meters to Square Feet
- Gravel Calculator - Area to cubic yards, tons and coverage
- Topsoil Calculator - Cubic yards, weight and coverage for any area
- Multiplication Facts - Any two numbers from 1 to 9, with the working shown
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Values from the Formula (b = 4, h = 3)
| If a = | Surface area |
|---|---|
| 1 | 38 square units |
| 2 | 52 square units |
| 3 | 66 square units |
| 4 | 80 square units |
| 5 | 94 square units |
| 10 | 164 square units |
Geometry Formulas: Area, Volume, Perimeter
These are the formulas for the area, perimeter, circumference, volume and surface area of the standard shapes — 31 of them. Each page shows not only the formula but where it comes from, what every letter stands for, two worked examples and the mistake that this particular shape invites. For example, it can help you find out what is the formula for the surface area of a rectangular prism? (The answer is: S = 2 · (a·b + a·h + b·h)). Pick the pair — "Area of a circle", for instance — and hit the "Find out" button.
Geometry Formulas: Area, Volume, Perimeter