SURFACE SCIENCE TOOLS
Contact Angle to Surface Energy Calculator
Use your measured contact angles to calculate surface free energy with OWRK or Fowkes, or critical surface tension with Zisman. Works with measurements from any goniometer.
Written by
Gurdeep Singh Saini
Holds a BASc in Mechanical Engineering from Ryerson University (now Toronto Metropolitan University) and an MASc from York University. He develops the automatic edge and baseline detection behind the Dropometer's analysis.
COO at Droplet Lab
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Reviewed by
Dr Alidad Amirfazli
Dr. Amirfazli, a leading expert in surface wetting and superhydrophobic coatings, has 250+ publications, edits Advances in Colloid and Interface Science, and has received multiple research awards.
Scientific Advisor & Co-founder
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Choose a calculation method
Measured contact angles
Choose a method and enter angles measured on the same specimen under the same conditions. Fields marked * are required. Your measurements stay in your browser.
Liquid values are approximate reference values at 20–25 °C, in mN/m. Confirm them against the liquid table used by your laboratory; edit the values below when needed.
Calculated results
Recorded inputs
Reference liquid values
Liquid values are approximate reference values at 20–25 °C, in mN/m. Confirm them against the liquid table used by your laboratory; edit the values below when needed.
| Liquid | Total (mN/m) | Dispersive (mN/m) | Polar (mN/m) |
|---|---|---|---|
| Water | 72.8 | 21.8 | 51 |
| Diiodomethane | 50.8 | 50.8 | 0 |
| Ethylene glycol | 48 | 29 | 19 |
| Glycerol | 64 | 34 | 30 |
| Formamide | 58 | 39 | 19 |
| 1-Bromonaphthalene | 44.6 | 44.6 | 0 |
| Hexadecane | 27.5 | 27.5 | 0 |
How the calculation works
OWRK fits a geometric-mean model to all liquids simultaneously. Fowkes uses a nonpolar reference to solve the dispersive component first, then uses polar liquids to estimate the polar component. Zisman fits cos(θ) against liquid surface tension and extrapolates to cos(θ) = 1.
γL(1 + cos θ) = 2√(γSᵈ γLᵈ) + 2√(γSᵖ γLᵖ)
Zisman critical surface tension is a wettability measure, not a polar/dispersive surface-energy split. Three or more liquids from a suitable chemical series help assess the fit. Two points alone cannot assess fit quality.
Scientific references
- Owens, D. K., and Wendt, R. C. (1969). Estimation of the surface free energy of polymers. Journal of Applied Polymer Science, 13(8), 1741–1747.
- Fowkes, F. M. (1964). Attractive forces at interfaces. Industrial & Engineering Chemistry, 56(12), 40–52.
- Zisman, W. A. (1964). Relation of the equilibrium contact angle to liquid and solid constitution. Advances in Chemistry, 43, 1–51.
Frequently asked questions
Yes. The calculation uses your measured angle and the liquid surface-tension values; it is independent of the instrument manufacturer.
Liquid ratios must identify the chosen model. Identical liquid ratios, invalid tensions or a negative fitted component cannot provide a physically valid result. The calculator asks you to check those inputs rather than silently flooring them to zero.
OWRK fits all liquids together. Fowkes first fixes the dispersive contribution using a nonpolar reference and estimates the polar contribution from the remaining liquids. Measurement scatter and model assumptions can cause different results.
No. Zisman estimates the liquid surface tension at complete wetting. It does not resolve polar and dispersive components and should not be reported as an OWRK surface-energy result.
Need help with your surface measurements?
Talk to a Droplet Lab application specialist about your measurements and experimental setup.
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