mN/m
millinewton per meter
Spring constantSurface tensionexact by definition
The millinewton per metre is 10⁻³ N/m, exact by prefix. It is the stiffness scale of soft atomic force microscope cantilevers, optical traps and biological molecules under load, where a single protein unfolds against forces of tens of piconewtons.
| 1 mN/m (Spring constant) | 0.001 N/m |
| 1 mN/m (Surface tension) | 1 mN/m |
As a unit of surface tension
The millinewton per metre is exactly 0.001 N/m, an exact prefix relation. It is the standard modern unit for surface tension because it puts common liquids in a readable range: water is 72.8 mN/m at 20 °C, ethanol 22.3, and mercury about 486.
Solvers that use spring constant