Math Education

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Surface Area of a Rectangular Prism: Formula & Examples

Published: 11.07.2026·Updated: 11.07.2026
Dewi Lestari

Dewi Lestari

Mathematics Specialist

Surface Area of a Rectangular Prism: Formula & Examples

The surface area of a rectangular prism (cuboid) is A = 2 × (l·w + l·h + w·h), where l = length, w = width, and h = height. A cuboid has 6 rectangular faces in three congruent pairs. Quick example: a cuboid with l = 8 cm, w = 5 cm, h = 4 cm has a surface area of 2 × (40 + 32 + 20) = 184 cm².

Rectangular Prism l h w 2(lw+lh+wh)
A cuboid has 3 pairs of congruent faces: l×w, l×h, and w×h.

How to Calculate the Surface Area of a Cuboid + Worked Example

A cuboid has three pairs of congruent faces: top & bottom (l × w), front & back (l × h), and left & right (w × h). The surface area is twice the sum of the three:

Worked example: A gift box shaped like a cuboid is 10 cm long, 6 cm wide, and 4 cm high. What is the minimum area of paper needed to wrap it?

Step 1: l = 10, w = 6, h = 4. Step 2: lw = 60, lh = 40, wh = 24. Step 3: A = 2 × (60 + 40 + 24) = 2 × 124 = 248 cm².

So at least 248 cm² of wrapping paper is required.

Why It Matters

The surface area of a cuboid is taught in Grade 8 (solids with flat faces) and is useful in real life — estimating cardboard for boxes, paint for a room's walls, or paper to wrap a present. Mastering it builds spatial reasoning and is the foundation for the volume of a cuboid and other solids like cubes and prisms.

See also: Surface Area of a Cube, Surface Area of a Cylinder, and Surface Area of a Sphere. Browse everything at Algonova Mathematics.

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