Convert surface tension between newton/metre, millinewton/metre and dyne/centimetre.
Fluids • 5 units
All 5 units on the Surface Tension Converter are defined against the Newton/meter (N/m), so each result is one conversion factor away from a single reference rather than the end of a chain of roundings.
The conversion this page is most often opened for is ready before you type anything: 1 N/m = 1,000 dyn/cm. Change either side and every row in the table recalculates with it.
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The practical range of this quantity is narrow enough that only two of the table's rows see much use. Newtons per metre is the SI form, but almost all published values are in millinewtons per metre or the numerically identical dynes per centimetre, so 1 N/m is 1,000 dyn/cm and most real liquids fall between 20 and 75 on that scale. The pound-force rows are far coarser than the measurement warrants, which is why they appear in almost no modern datasheet.
How the value was measured changes what it means. Ring and plate methods pull a probe through the interface and report an equilibrium value; pendant-drop and maximum-bubble-pressure methods can be run fast enough to capture dynamic surface tension, which is what a surfactant solution shows before its molecules have had time to reach a newly created surface. On a fast coating or printing line, the interface is milliseconds old, so the effective tension is closer to that of the pure solvent than to the equilibrium figure on the label.
Wetting depends on the comparison between a liquid's surface tension and a solid's surface energy, both quoted in the same millinewtons per metre. Untreated polyethylene sits near 31 mN/m and PTFE near 18, so an ink or adhesive above those values beads instead of spreading — which is exactly what corona and flame treatment are for, and what dyne pens are calibrated in. Reading a treatment specification is therefore reading this page's units applied to a solid rather than a liquid.
Quick reference — 1 Newton/meter (N/m) is equal to:
| Millinewton/meter | mN/m | 1,000 |
| Dyne/centimeter | dyn/cm | 1,000 |
| Pound-force/foot | lbf/ft | 0.0685217796 |
| Pound-force/inch | lbf/in | 0.0057101483 |
5 units of surface tension, each a fixed multiple of the N/m. The table spans 175,127:1, from mN/m (0.001 N/m) to lbf/in (175.127 N/m). Conversion is one multiplication into the base unit and one division out of it, with no lookup table and no approximation.
value_to = value_from × (factor_from ÷ factor_to)1 N/m = 1 N/m1 mN/m = 0.001 N/m1 dyn/cm = 0.001 N/m1 lbf/ft = 14.5939 N/m1 lbf/in = 175.127 N/mwhere:
Assumptions: Factors are exact definitions. Full double precision is carried internally and rounding is applied only for display.
Result25 N/m = 25000 dyn/cm
Surface tension can be read two ways that turn out to be the same thing: force per unit length along a line in the surface, or energy per unit area of surface created. Newtons per metre and joules per square metre are dimensionally identical, and both appear on datasheets.
Water's 0.0728 N/m at 20 °C is unusually high for a small molecule, and it is why water beads on a waxed surface while alcohol spreads. Surfactants work by lowering it, which is the entire mechanism of detergency. The CGS unit, dynes per centimetre, is numerically equal to millinewtons per metre — so 72.8 dyn/cm and 72.8 mN/m are the same measurement, a rare case where the older unit converts without arithmetic.