Surface Tension & Capillary Rise Calculator

Interfacial Chemistry, Capillarity & Surface Tension Metrology

Surface Tension is the energy required to increase the surface area of a liquid by one unit:

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• Universal Surface Tension Conversion Formulas (IUPAC Standards)**:

1 mN/m 1 dyn/cm 1 mJ/m^2 = 0.001 N/m = 0.001 J/m^2

γ_lbf/ft = γ_N/m14.593903 = γ_N/m × 0.0685218

γ_lbf/in = γ_N/m175.126835 = γ_N/m × 0.00571015

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• Jurin's Law of Capillary Rise & Young-Laplace Equation**:

h = (2 γ θ) / (ρ × g × r) (Capillary Rise Height in mm)

Δ P = (2 γ) / (r) (Young-Laplace Droplet Excess Pressure in Pascals)

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• Standard Liquid Interface Benchmarks (@ 20°C)**:

• Pure Ethanol: 22.10 mN/m 22.10 dyn/cm h = 11.42 mm

• Detergent SDS Solution: 30.00 mN/m 30.00 dyn/cm h = 12.24 mm

• Human Blood Plasma: 58.00 mN/m 58.00 dyn/cm

• Pure Liquid Water: 72.80 mN/m 0.07280 N/m h = 29.74 mm

• Liquid Mercury (Hg): 486.5 mN/m θ = 140^ h = -11.47 mm (Capillary depression)

How to Use This Calculator

Enter your Surface Tension Magnitude (γ / σ) (e.g. 72.8 in tension), From Surface Tension Unit — choose from Millinewtons per Meter (mN/m = dyn/cm = mJ/m² - Interfacial Standard), Newtons per Meter (N/m = J/m² - SI Base Unit), Dynes per Centimeter (dyn/cm - CGS Unit), To Surface Tension Unit — choose from Newtons per Meter (N/m), Millinewtons per Meter (mN/m = dyn/cm), Pound-Force per Foot (lbf/ft), Capillary Tube Radius (r in mm) (e.g. 0.50 in mm), Contact Angle (θ in degrees, 0° = complete wetting) (e.g. 0 in °), Liquid Density (ρ in kg/m³) (e.g. 998 in kg/m³), and Liquid Interface Benchmark — choose from Custom Surface Tension, Pure Water @ 20°C (72.80 mN/m = 72.8 dyn/cm, ρ=998) → Capillary Rise = 29.74 mm | ΔP = 291.2 Pa, Liquid Mercury @ 20°C (486.5 mN/m, θ=140°, ρ=13546) → Capillary Depression = -11.47 mm. Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Jurin's Law Capillary Height: h = (2 gamma cos(theta)) / (rho g r)

Young-Laplace Droplet Excess Pressure: Delta_P = 2 * gamma / r (in Pascals)

Worked Example

A microfluidics engineer calculating capillary action for pure water inside a 0.50 mm radius tube finds the water climbs 29.74 mm against gravity under Jurin's Law.

Understanding Your Result

Unit conversions are exact by definition within a given measurement system (e.g., 1 km = exactly 1,000 m). Cross-system conversions (metric to imperial) use defined exchange factors: 1 inch = exactly 2.54 cm; 1 pound = 0.45359237 kg. Round your converted result to match the precision of your original measurement — expressing more decimal places than your input justifies implies false accuracy. For regulatory, legal, or safety-critical applications, verify which measurement system is required by the applicable standard.