Stress Converter
Convert between Pascals, MPa, GPa, N/mm², psi, ksi and more. Designed for structural and mechanical engineers working across SI and imperial specifications.
| Material | Yield strength | Tensile strength | Standard |
|---|---|---|---|
| Structural steel S275 | 275 N/mm² | 410–560 N/mm² | BS EN 10025 |
| Structural steel S355 | 355 N/mm² | 470–630 N/mm² | BS EN 10025 |
| Concrete C25/30 | — | 25 N/mm² (fck) | Eurocode 2 |
| Aluminium 6061-T6 | 276 N/mm² | 310 N/mm² | ASTM B209 |
| Grade 8.8 bolt | 640 N/mm² | 800 N/mm² | ISO 898-1 |
Common Stress Conversion Questions
What is the difference between stress and pressure?
Both are force per unit area and share the same units (Pa, N/mm²). Pressure is a scalar acting uniformly in fluids. Stress is a tensor describing internal forces in solids — it can be tensile (pulling apart), compressive (squeezing together) or shear (sliding). Stress is the quantity used in structural analysis and material testing.
Is N/mm² the same as MPa?
Yes — 1 N/mm² = 1 MPa exactly. N/mm² is simply the expression of the unit in terms of Newtons and millimetres rather than the SI prefix system. Both are used interchangeably in UK structural engineering documentation, Eurocodes and British Standards.
What is the yield strength of S355 steel in psi?
S355 structural steel has a yield strength of 355 N/mm² (MPa). Converting: 355 MPa × 145.038 = approximately 51,489 psi (or 51.5 ksi). This conversion is useful when working with US-origin design software or AISC-based specifications.
How do you convert psi to MPa?
1 psi = 0.00689476 MPa. Multiply psi by 0.006895 to get MPa. To go the other way: 1 MPa = 145.038 psi. For example, 10,000 psi (a common pump or hydraulic fitting rating) = 68.95 MPa.
What are typical concrete strengths in N/mm²?
In UK construction (Eurocode 2 notation), concrete is specified by its characteristic cylinder/cube strength: C20/25 (20/25 N/mm²), C25/30, C30/37, C32/40. Foundations typically use C25/30; exposed structural elements may require C30/37 or higher for durability.