Calculates a cube’s volume, surface area, and space diagonal from its side length.
How it works
Volume is the side length cubed, surface area is six times the side squared (one for each face), and the diagonal uses the Pythagorean theorem extended into three dimensions.
What this does not include
This does not include other 3D shapes — for cubes alongside spheres, cylinders, and cones, use this site’s general surface area calculator instead.
How to use this calculator
- Enter the cube’s side length.
A worked example
Side length 4: volume = 4³ = 64, surface area = 6 × 4² = 96, space diagonal = 4√3 = 6.9282.
Side length 6: volume = 216, surface area = 216 — volume and surface area happen to share the same number at this particular size, a coincidence of this specific side length, not a general rule.
What the outputs mean
| Output | Formula |
|---|---|
| Volume | side³ |
| Surface area | 6 × side² (one term per face) |
| Space diagonal | side × √3 |
Edge cases worth knowing
Doubling the side multiplies volume by 8, not 2 — volume scales with the cube of a linear dimension, the same reason a “slightly bigger” storage box holds far more than it looks like it should.
The space diagonal is longer than any single face’s diagonal. A face diagonal only crosses one square face (side × √2); the space diagonal cuts through the interior corner-to-corner, one dimension further.
Frequently asked questions
Why does a cube have six faces?
A cube is bounded by six identical square faces — one on each side (top, bottom, front, back, left, right).
What’s the space diagonal, exactly?
The longest straight line that fits inside the cube, running from one corner through the interior to the opposite corner.
How does volume scale if I double the side length?
Volume scales with the cube of the side length, so doubling the side multiplies the volume by 8, not just 2.
