Best for
Coatings and heat transfer
Surface area is often the starting point for paint, plating, insulation, and heat exchange estimates.
Engineering formula reference
Surface Area Formula Sheet
Search surface area formulas for common 3D shapes used in heat transfer, coatings, material estimates, tank design, and engineering geometry.
3D geometry
Search surface area formula sheet
Filter the formula table by shape, variable, symbol, expression, or engineering use case.
Choose the right area
Total vs lateral area
Some applications need total surface area, while others only need side or wetted area.
Formula reference
Surface area formulas with variables
| Shape | Surface area formula | Variables and notes |
|---|---|---|
| Cube | SA = 6a2 | a = side length |
| Rectangular prism | SA = 2(lw + lh + wh) | l = length, w = width, h = height |
| Sphere | SA = 4πr2 | r = radius |
| Cylinder | SA = 2πrh + 2πr2 | Total area including both ends |
| Cone | SA = πr2 + πr l | l = slant height |
| Triangular prism | SA = P h + 2A | P = base perimeter, A = base area |
| Hollow cylinder | SA = 2πh(R + r) + 2π(R2 - r2) | Includes inner, outer, and end annulus areas |
How to use
Practical engineering checks
Coating estimate
material = SA / coverage
Use total exposed surface area and the coating coverage rate.
Heat transfer
Q = U A ΔT
A is heat transfer area in many simplified thermal estimates.
Cylinder total area
SA = 2πrh + 2πr2
Side area plus two circular ends.
Units
area units are squared
Square unit conversions before comparing values.
Definitions
Symbols and variables explained
SA
Total surface area unless the row states lateral or curved area.
r
Radius of a circle, sphere, cylinder, or cone base.
l
Slant height for a cone.
P
Perimeter of the prism base.
FAQ
Surface Area Formula Sheet questions
How do I use this formula sheet?
Find the shape or identity, confirm each variable definition, keep units consistent, then substitute values into the formula.
Are these formulas exact?
The basic geometry formulas are exact for ideal shapes. Rows marked approximate depend on simplified geometry, thin-wall assumptions, or ignoring radii and fillets.
Can I use these formulas for final engineering design?
Use them as calculation references. Final design should also check loads, materials, tolerances, safety factors, and any governing standards.
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