      Last reviewed: May 8, 2026
    

Interactive Analysis Tools

Porosimetry Calculators

Essential calculation tools for pore structure analysis. Convert between units, calculate pore sizes from pressure data, determine surface areas, and validate bubble points — all based on industry-standard equations and ISO/ASTM methodologies.

Washburn Pore Size Calculator (MIP)

Calculate pore diameter from mercury intrusion pressure using the Washburn equation

Applied Pressure

Surface Tension (mN/m or dynes/cm)

Contact Angle (degrees)

Washburn Equation

d = |4γ cos θ / P|

Where:
d = pore diameter (μm)
γ = surface tension (mN/m)
θ = contact angle (degrees)
P = pressure (MPa)

CALCULATED PORE DIAMETER

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BET Surface Area Calculator

Calculate specific surface area from monolayer capacity and adsorbate properties. Have raw isotherm points instead? Use the multi-point BET calculator.

Monolayer Capacity (cm³/g STP)

Adsorbate Gas

Cross-Sectional Area (Ų)

BET Equation

S = (V_m × N_A × A_m) / M_v

Where:
S = surface area (m²/g)
V_m = monolayer volume
N_A = Avogadro's number
A_m = molecular area
M_v = molar volume (22414 cm³)

BET SPECIFIC SURFACE AREA

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Bubble Point Calculator (CFP)

Calculate largest through-pore diameter from bubble point pressure

Bubble Point Pressure

Wetting Fluid

Surface Tension (dynes/cm)

Young-Laplace Equation

d = 4γ cos θ / ΔP

For complete wetting (θ = 0°):
d = 4γ / ΔP

Bubble point = largest through-pore
ASTM F316 uses an empirical constant: d[μm] = 2860·γ/p[Pa] (= 0.415·γ/p[psi]), about 0.715 × the ideal value

MAXIMUM PORE DIAMETER

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Unit Converters

Quick conversion between common pressure and pore size units

Pressure Converter

From

Pore Size Converter

From

Worked calculation guides

Washburn equation — pressure-to-pore-size conversion with worked examples
Multi-point BET calculator — paste isotherm points, get C, n_m and S_BET with Rouquerol checks
BJH pore size distribution — Kelvin radius, film thickness and dV/dlogD
Total pore volume & average pore diameter (4V/A)
t-plot micropore volume & external surface area
Bubble point & mean flow pore size
Reading a mercury porosimetry report — densities, porosity, median pore diameter

Quick Reference

Common Constants & Values

Mercury Properties (25 °C)

Surface tension: 485 mN/m
Contact angle: 130–140° (assumed)
Density: 13.534 g/cm³

N₂ at 77 K

Cross-section: 16.2 Å²
P₀: 101.3 kPa
Molar volume: 22414 cm³

Ar at 87 K

Cross-section: 13.8 Å² (ISO 9277)
P₀: ≈101.3 kPa (87.3 K = Ar boiling point)
Better for micropores

Constants

N_A: 6.022 × 10²³
R: 8.314 J/(mol·K)
1 atm = 101.325 kPa