What is the correct area to use in a stress calculation for a compressed object?

[1question]

Homework Statement

In a simple mechanics question, which area should be used for a stress calculation? ex. A brick is compressed on 2 sides (opposite to each other) by a given compressive force F. The area of each of the sides being compressed is A.

Homework Equations

σ = F/A

The Attempt at a Solution

I'm just confused if it should be σ = F/A OR σ = F/(2A) and why.

 

[1question]

It's just σ = F/A. I forgot that A is cross-sectional area.