Classroom

Viscosity Definitions

Viscometer Shear Rate Data

Download Unit Conversion Program

Conversions and Calculations

Understanding Uncertainty

Basic Viscosity
Shear Stress / Shear Rate = Viscosity


General
a = 9.801 m/s²


Dynamic Viscosity
1 poise = 1 g/cm·s = 0.1 N·s/m² = 0.1 Pa·s
1 cP = 1 mPa·s


SI Unit Conversion
1 Pascal = 1 Newton / m²


Kinematic Viscosity
1 Stoke = 1 cm²/s = 100 mm²/s
1 cSt = 1 mm²/s


Conversion from Rotational to Kinematic Viscosity
Poise / Density = Stoke
g/cm·s / g/cm³ = cm²/s


Conversion from Kinematic to Rotational Viscosity
Stoke * Density = Poise
cm²/s * g/cm³ = g/cm·s


Conversion from Kinematic to Saybolt Viscosity




Krebs Unit (for Thomas^®-Stormer Viscometer)
Over the viscosity range of 200 to 2100 mPa·s (cP)
ln(KU) = 1.1187 + 0.8542*ln(0.1938v + 36) - 0.0443(ln(0.1938v +36))²

Over the viscosity range of 2100 to 5000 mPa·s (cP)
ln(KU) = 1.8118 + 0.596*ln(0.1938v + 36) - 0.0206(ln(0.1938v +36))²

Where KU is the viscosity in Krebs Units at 25°C
and v is the viscosity in mPa·s (cP) at 25°C