Viscosity Calculator (Chemistry)

Viscosity describes how resistant a fluid is to flow — a property that matters in everything from engine oil selection to chemical processing. The Viscosity Calculator offers three modes: select Kinematic ↔ Dynamic Viscosity to convert between the two using fluid density, choose Viscosity at Temperature to predict viscosity at a target temperature from two known data points, or use Viscosity Index to measure how much a fluid's viscosity changes with temperature from its 40°C and 100°C values.

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°C
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Results

Primary Result

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Secondary Result

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Viscosity Index

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Frequently Asked Questions

What is the difference between kinematic and dynamic viscosity?

Dynamic viscosity (measured in cP or mPa·s) is the absolute resistance to flow, while kinematic viscosity (measured in cSt or mm²/s) is dynamic viscosity divided by fluid density. Kinematic viscosity represents how fast a fluid flows under gravity.

How does temperature affect viscosity?

Viscosity decreases as temperature increases for most liquids. This relationship follows the Andrade equation and can be used to predict viscosity at different temperatures when you know viscosity at two reference points.

What is viscosity index and why is it important?

Viscosity Index (VI) measures how much a fluid's viscosity changes with temperature. Higher VI values indicate less viscosity change with temperature, which is desirable for lubricants that must perform across varying temperatures.

What units are commonly used for viscosity measurements?

Common units include centistokes (cSt) for kinematic viscosity, centipoise (cP) for dynamic viscosity, and SI units like mm²/s and mPa·s. The calculator converts between these units automatically.

How accurate are calculated viscosity values?

Calculated values are estimates based on established correlations like the Andrade equation. For critical applications, always verify theoretical calculations with actual viscometer measurements under real operating conditions.

What is the typical viscosity range for different fluids?

Water has about 1 cP at room temperature, light oils range from 10-100 cP, heavy oils can be 100-1000 cP, and very thick fluids like honey can exceed 10,000 cP.