What temperature range is supported?

The calculator supports liquid water from 0 °C (32 °F) to 100 °C (212 °F) at atmospheric pressure. Above 100 °C water is steam, and the formula no longer applies.

What formula is used for dynamic viscosity?

The Vogel empirical correlation: ln(μ) = A + B / (C + T), where T is in Kelvin and A, B, C are fitted constants (A = −3.7188, B = 578.919, C = −137.546). This gives results within 1% of IAPWS tabulated values over 0–100 °C.

What is the difference between dynamic and kinematic viscosity?

Dynamic viscosity (μ) measures a fluid's resistance to shear stress and is expressed in mPa·s (or equivalently cP). Kinematic viscosity (ν) is dynamic viscosity divided by fluid density and is expressed in mm²/s (or cSt). Kinematic viscosity is used in Reynolds number calculations.

Why does viscosity decrease as water gets hotter?

Higher temperature gives water molecules more thermal energy, weakening the intermolecular hydrogen bonds that resist flow. As a result, hot water flows more easily (lower viscosity) than cold water.

What units does the tool output?

Dynamic viscosity is shown in mPa·s and centipoise (cP) — they are numerically equal. Kinematic viscosity is shown in mm²/s and centistokes (cSt) — also numerically equal.

Water Viscosity Calculator

Enter a water temperature and instantly get dynamic and kinematic viscosity values using the Vogel and IAPWS empirical formulas.

Temperature Input

Unit:

Temperature

°C

Valid range: 0 °C to 100 °C

Pipe Diameter (optional, for Reynolds number)

Flow Velocity (optional)

m/s

Viscosity Results

Dynamic Viscosity (μ)

—

mPa·s (= cP)

— Pa·s

Kinematic Viscosity (ν)

—

mm²/s (= cSt)

— m²/s

Water Density (ρ)

—

kg/m³

Temperature

—

Reference Table

Temp (°C)	μ (mPa·s)	ν (mm²/s)	ρ (kg/m³)

Summary

This calculator determines the dynamic viscosity (in mPa·s or cP) and kinematic viscosity (in mm²/s or cSt) of liquid water at a specified temperature between 0 °C and 100 °C. It uses the Vogel empirical correlation for dynamic viscosity and the known density of water to derive kinematic viscosity. Results are useful in pipe flow analysis, heat transfer design, hydraulic calculations, and any engineering application involving water transport.

How it works

Enter the water temperature in either Celsius or Fahrenheit.
The tool applies the Vogel empirical equation to calculate dynamic viscosity.
Water density at that temperature is estimated using a polynomial fit.
Kinematic viscosity is derived by dividing dynamic viscosity by density.
Results are shown in SI units (mPa·s, mm²/s) and US/CGS equivalents (cP, cSt).
Reynolds number and flow regime are indicated for a reference pipe diameter if provided.

Use cases

Pipe flow and pressure drop calculations in plumbing and HVAC design.
Pump selection and hydraulic system sizing.
Heat exchanger and thermal system design.
Verifying Nusselt and Reynolds number correlations.
Environmental and civil engineering water modeling.
Laboratory fluid mechanics reference checks.
Irrigation and agricultural water system engineering.
Teaching and student reference for fluid mechanics courses.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu