Stress (σ) is used to state the amount of force per area. The stress is usually (according to SI) displayed in MPa (MegaPascal) which is equal to N/mm^{2} (Newtons / square millimeters).

\[ \sigma = \frac {F}{A_0} \]

Perhaps the most important aspect to keep into focus when calculating a design is the distribution of stress. In an ideal situation every fiber of the material is utilized or loaded to the same amount preventing excessive material usage. Reducing the amount of material used in a design is a noble goal but also introduces risk when not thoroughly supported by calculations.

Stress can be induced by compression or tension forces. In an situation with non complex forces, like axial tension force on a solid rod, stress can be determined by dividing force by section area. In examples where there is deflection involved, stress can be calculated with the use of the section modulus.

\[ \sigma_{max} = \frac{M_b}{W_b} \]

On this page multiple tools are presented which can be used to determine stress and strain. This could involve stress as a result of bending load which is one of the most inefficient uses of material. This because a significant portion of the material is not utilized. But also shear stress and homogeneous strain are given attention.