Cuboid Calculator (Rectangular Prism)

A rectangular prism, also called a cuboid, is a three-dimensional solid with six rectangular faces. Every pair of opposite faces is identical, and all interior angles are 90°. Common real-world examples include bricks, boxes, books, and rooms.

Multiply the three dimensions together: V = length × width × height. For example, a box measuring 10 cm × 6 cm × 4 cm has a volume of 240 cm³. The result is always expressed in cubic units.

The total surface area formula is S = 2(lw + lh + wh), where l is length, w is width, and h is height. This accounts for all six rectangular faces in three pairs. The lateral surface area (the four side faces only) is S_lat = 2h(l + w).

The space diagonal runs from one corner to the opposite corner through the interior. Use the 3D Pythagorean theorem: d = √(l² + w² + h²). It is the longest straight-line distance that fits inside the box.

Total surface area includes all six faces of the cuboid. Lateral surface area includes only the four vertical side faces, excluding the top and bottom. Lateral SA = 2h(l + w), while Total SA = 2(lw + lh + wh).

You can select any length unit — mm, cm, m, km, in, ft, or yd. Volume results are expressed in the cube of that unit (e.g., cm³) and area results in the square of that unit (e.g., cm²). The calculator does not convert between units, so make sure all three dimensions use the same unit.

Yes. A cube is a rectangular prism where all three dimensions are equal (l = w = h). Every formula for a rectangular prism applies to a cube — for example, a cube with side 5 cm has volume 125 cm³ and surface area 150 cm².

A rectangular prism has 6 faces (all rectangles), 12 edges, and 8 vertices. The edges come in three groups of 4 parallel edges, each group sharing the same length as one of the three dimensions.