A net is a flat pattern that folds up into a 3D shape. By calculating the area of each face in the net and adding them together, you find the total surface area.

What Is a Net?

Imagine cutting along the edges of a cardboard box and unfolding it flat. The flat shape you get is the net. Every 3D shape has at least one net.

Cube Net

A cube has 6 identical square faces. Its net shows 6 squares arranged in a cross shape.

SA = 6s²
Each face has area s², so total = 6 × s².

Rectangular Prism Net

A rectangular prism unfolds into 6 rectangles — 3 pairs of identical faces.

SA = 2(lw + lh + wh)

Cylinder Net

A cylinder unfolds into two circles + one rectangle. The rectangle's width equals the circumference of the circle (2πr) and its height is h.

SA = 2πr² + 2πrh

Cone Net

A cone unfolds into one circle + one sector. The sector's arc length equals the base circumference.

SA = πr² + πrl (where l = slant height)

Pyramid Net

A square pyramid unfolds into 1 square base + 4 identical triangles.

SA = s² + 2sl (where l = slant height)

Why Nets Work

Nets work because surface area is the sum of all face areas. Whether the faces are folded or flat, their areas don't change. This is why cone surface area from nets and cylinder surface area from nets give the same answer as the formulas.

Try our Cube, Cylinder, Cone, and Pyramid calculators. See all formulas and common mistakes.