What is Young's modulus?

Young's modulus (E) is the ratio of tensile stress to tensile strain in the elastic region — it measures stiffness. A high E means the material resists stretching: steel at about 200 GPa is roughly three times stiffer than aluminium at 69 GPa.

How are E, G, and Poisson's ratio related?

For an isotropic material they obey E = 2G(1 + ν), where G is the shear modulus and ν is Poisson's ratio. Knowing any two lets you compute the third, which is why this table lists all three together.

How do I get strain from stress?

Hooke's law gives strain = stress / E. With both in the same units (the tool converts MPa stress and GPa modulus consistently), strain is dimensionless. Multiply by 100 for percent elongation, or by the length for total stretch.

What is Poisson's ratio?

Poisson's ratio is how much a material contracts sideways when stretched lengthwise. Most metals sit near 0.3, meaning a 1 percent stretch produces about 0.3 percent narrowing. Cork is near zero and rubber approaches the incompressible limit of 0.5.

Does modulus change with temperature or alloy?

Yes, but weakly for small changes. Young's modulus falls slowly as temperature rises and varies only a little between alloys of the same base metal, so all carbon and alloy steels share roughly 200 GPa. Use a temperature-corrected value for high-heat work.

Young's Modulus Reference Table

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Young’s modulus tells you how stiff a material is — how much it stretches under load. This reference lists Young’s modulus, shear modulus, and Poisson’s ratio for common materials and computes elastic strain from an applied stress using Hooke’s law.

How it works

In the elastic region stress and strain are proportional, and the constant of proportionality is Young’s modulus E:

strain = stress / E

For an isotropic material the three elastic constants are linked by:

E = 2 * G * (1 + ν)

so the shear modulus G and Poisson’s ratio ν are not independent of E. The calculator takes a stress in MPa, divides by E (converted to MPa), and reports the dimensionless strain and its percent elongation. A 250 MPa stress in steel (E ≈ 200000 MPa) gives a strain of 250 / 200000 = 0.00125, about 0.125 percent.

Tips and notes

Stay in the elastic region: Hooke’s law only holds below the yield stress, so treat large computed strains with suspicion.
All carbon and alloy steels share roughly 200 GPa — alloying changes strength far more than stiffness.
Most metals have Poisson’s ratio near 0.3; rubber approaches the incompressible limit of 0.5.
Modulus drops slowly with temperature; use a corrected value for hot or cryogenic service.