Surface Area Calculator
Wrapping a Box in Numbers
A rectangular box (cuboid) has six faces arranged in three matching pairs — top and bottom, front and back, left and right. Total surface area adds up all six, which simplifies to doubling the sum of the three distinct face areas.
The Formula
Surface Area = 2(lw + lh + wh)
Worked Example
For a box with length 4, width 3, and height 5:
| Face Pair | Area |
|---|---|
| l × w (×2) | 2 × 12 = 24 |
| l × h (×2) | 2 × 20 = 40 |
| w × h (×2) | 2 × 15 = 30 |
| Total | 94 |
Where This Matters
- Paint and material coverage — surface area sets how much paint, laminate, or wrap a box-shaped object needs.
- Packaging and cardboard — the flat sheet area required to fold into a box comes straight from this calculation.
- Heat transfer — the surface area of an enclosure affects how quickly it gains or loses heat.
How to Use This Calculator
- Enter the Length.
- Enter the Width.
- Enter the Height.
- Select Calculate to get the total surface area.
Related Calculations
Need just the sides, not the top and bottom? Use the Lateral Area Calculator, or find the enclosed volume with the Rectangular Prism Volume Calculator.