📦 Rectangular Prism Calculator
Calculate the volume, surface area, and space diagonal of a rectangular prism (box) from its length, width, and height.
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What this calculator finds
A rectangular prism (a box shape) has three key measurements: how much space it holds (volume), how much material covers its outside (surface area), and the longest straight line that fits inside it (the space diagonal).
The formulas
Volume is V = l × w × h. Surface area is SA = 2(lw + lh + wh), the sum of the areas of all six rectangular faces. The space diagonal is d = √(l² + w² + h²), found with a 3D extension of the Pythagorean theorem.
This is useful for packing, shipping, storage, and construction planning. Results are for general estimation purposes.
Last reviewed August 2026