Constants & Conversions — Cheat Sheet
Physical constants, material properties and SI prefixes on one page.
Physical constants
| Gravity g | 9.80665 m/s² |
| Gas constant R | 8.314 J/mol·K |
| Stefan-Boltzmann σ | 5.670×10⁻⁸ W/m²K⁴ |
| Atmosphere | 101.325 kPa = 1 atm |
| Water density | 1000 kg/m³ (4 °C) |
| Absolute zero | 0 K = −273.15 °C |
Steel (typical)
| Modulus E | 200–210 GPa |
| Shear modulus G | 79 GPa |
| Poisson's ν | 0.29 |
| Density | 7850 kg/m³ |
| CTE α | 11.5–12.5 µm/m·°C |
Aluminium (typical)
| Modulus E | 69 GPa |
| Density | 2700 kg/m³ |
| Poisson's ν | 0.33 |
| CTE α | 23 µm/m·°C |
Key conversions
| 1 inch | 25.4 mm |
| 1 ksi | 6.895 MPa |
| 1 lbf | 4.448 N |
| 1 lbf·ft | 1.356 N·m |
| 1 hp | 745.7 W |
| 1 psi | 6.895 kPa |
SI prefixes
| G / M / k | 10⁹ / 10⁶ / 10³ |
| m / µ / n | 10⁻³ / 10⁻⁶ / 10⁻⁹ |
Formula reference — verify against the governing standard. Not a substitute for engineering judgment.