geometry calculator

Rectangular Prism Surface Area Calculator

This rectangular prism surface area calculator helps when length, width, height are already known and you want the surface area quickly.

Important Use Notice

Informational calculator only. Verify important outputs independently before legal, tax, medical, engineering, safety-critical, contractual, employment, or compliance use.

Estimate

Enter job values, review the estimate, then use the decision hints before ordering or quoting.

Estimate Results

Enter values to see the result.

Formula

surface area = 2(lw + lh + wh)

Add the areas of the three face pairs and double the sum.

This measures the outer covering area of the solid.

Example

10 units, 6 units, 4 units gives Surface Area 248.

Check

Mixing units or scales across length, width, height before calculating surface area.
Rounding too early when the surface area still feeds another step.

Next Step