A tensile test, also known as a tension test, tests a material's strength. It's a mechanical test where a pulling force is applied to a material from both sides until the sample changes its shape or breaks. It's is a common and important test that provides a variety of information about the material being tested, including the elongation, yield point, tensile strength, and ultimate strength of the material. Tensile tests are commonly performed on substances such as metals, plastics, wood, and ceramics.

The tensile strength of a sample of material describes how it reacts when tension is applied to it. By measuring the changes in the material as tension is applied, engineers can determine a variety of things about the material, which is helpful in determining whether the material is a suitable choice for the application they have in mind. In addition to whether a material changes in shape, a tensile test will also show a material's "ultimate strength." The ultimate strength refers to the maximum tensile load that the material can stand. A tension test also uncovers the material's "yield point," which is the amount of tension that causes the sample to break or fail.

Tensile testing systems use a number of different units of measurement. The International System of Units, or SI, recommends the use of either Pascals (Pa) or Newtons per square meter (N/m²) for describing tensile strength. In the United States, many engineers measure tensile strength in kilo-pound per square inch (KSI).

Tensile test machines have been used commercially since the late 1800s. The earliest types of tensile test machine were hand operated. Modern versions that are used commercially, however, may incorporate computers and highly sensitive electrical components. These more advanced machines enable scientists and engineers to obtain extremely accurate measurements.

In addition to dedicated machines that perform only tensile testing procedures, there are versatile pieces of equipment called universal testing machines (UTMs). These UTMs can perform a variety of stress tests on material samples. A UTM may be equipped to perform a bending test, a compression test, and a tensile test on a single sample of material.

Tensile testing is vitally important in a number of industries, including mechanical engineering, structural engineering and architecture. During the planning stage of a building project, for example, these professionals normally calculate the stresses to which a building might be subjected. To ensure a stable construction, it is then necessary to select appropriate building materials, which will be able to withstand those stresses without breaking.