Find box surface area from length, width, and height
Result
Rectangular Prism Surface Area
Step-by-Step Derivation
Rectangular Prism Surface Area Formula
A = 2(lw + lh + wh)
A rectangular prism has three pairs of equal rectangular faces. The formula adds one of each face type, then doubles the sum to cover the whole outside.
⚠Length, width, and height must be positive and use the same unit. Surface area is measured in square units.
How Rectangular Prism Surface Area Works
Each dimension pair forms a rectangle: length by width, length by height, and width by height. Doubling covers the opposite matching faces.
Top and Bottom
These faces each have area lw.
Front and Back
These faces each have area lh.
Left and Right
These faces each have area wh.
Volume Check
The tool also reports lwh.
💡 Example: For l=8, w=5, and h=3, A=2(40+24+15)=158 square units.
Applications of Rectangular Prism Surface Area
WrappingPaintingPackagingConstruction
Frequently Asked Questions
What is a rectangular prism surface area calculator?▼
It calculates the total outside area of a box-shaped solid.
What is the rectangular prism surface area formula?▼
The formula is A = 2(lw + lh + wh).
How do I use this calculator?▼
Enter length, width, and height, then click Calculate to get surface area, volume, and diagonal.
Why are there three products in the formula?▼
The three products are the areas of the three different face pairs: lw, lh, and wh.
Where is rectangular prism surface area used?▼
It is used for wrapping, painting, packaging, construction, shipping, and material estimates.
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