Quick answer
Water's dynamic viscosity follows a Vogel-type fit, μ = 2.414 × 10⁻⁵ × 10^(247.8 ÷ (T − 140)) Pa·s with T in kelvin. At 0 °C it is 1.7531 mPa·s, accurate to about ±2.5%.
Enter a water temperature between 0 and 100 °C. The calculator returns the dynamic viscosity.
Related tools: Viscosity Calculator: Convert between dynamic viscosity (cP) and kinematic viscosity (cSt). Water Velocity Calculator: Water velocity in a pipe from flow and inside diameter. Reynolds Number Calculator: Reynolds number and flow regime in a pipe.
How to use the Water Viscosity Calculator
- Enter temperature (°C) (between 0 and 100).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Temperature | A number, in °C | ≥ 0, ≤ 100 |
Formula and method
Formula
μ = 2.414×10⁻⁵ × 10^(247.8 ÷ (T − 140)) Pa·s, T in kelvin
IEEE-754 double precision; shown to the decimals indicated.
Vogel-type correlation, accurate to about 2.5% between 0 and 100 °C.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Temperature = 0.
| Result | Value |
|---|---|
| Dynamic viscosity | 1.7531 mPa·s |
| Typical accuracy | about ±2.5% (Vogel correlation) |
Example 2
Inputs: Temperature = 20.
| Result | Value |
|---|---|
| Dynamic viscosity | 1.0017 mPa·s |
| Typical accuracy | about ±2.5% (Vogel correlation) |
Example 3
Inputs: Temperature = 40.
| Result | Value |
|---|---|
| Dynamic viscosity | 0.6514 mPa·s |
| Typical accuracy | about ±2.5% (Vogel correlation) |
The first line is the headline result (dynamic viscosity). Below it the water Viscosity Calculator lists typical accuracy, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Strong temperature effect
Viscosity falls from 1.75 mPa·s at 0 °C to about 1.0 at 20 °C and 0.28 at 100 °C. Warm water flows far more easily, which matters for heating systems and pumps.
Range
The fit holds for liquid water at atmospheric pressure from 0 to 100 °C. Dissolved salts and pressure change the value. Use the result with the Reynolds Number calculator.
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Temperature: entering "-5" shows "Temperature must be at least 0." beside that field and no result.
Choosing between the Water Viscosity Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Viscosity Calculator](/science/viscosity-calculator/) | convert, viscosity and fluid density | Kinematic viscosity |
| [Water Velocity Calculator](/science/water-velocity-calculator/) | flow and inside diameter | Velocity |
| [Reynolds Number Calculator](/science/reynolds-number-calculator/) | fluid density, flow velocity and pipe diameter | Reynolds number |
| [Flow Rate Calculator](/science/flow-rate-calculator/) | use | Flow rate |
| [Specific Gravity Calculator](/science/specific-gravity/) | density | Specific gravity |
Background: fluid flow
Volumetric flow rate is Q = A × v (cross-sectional area times average velocity). Bernoulli's equation, P + ½ρv² + ρgh = constant, holds along a streamline for steady, incompressible, frictionless flow, so real pipes need friction corrections. The Reynolds number Re = ρvL/μ compares inertia with viscosity.
Laminar flow in a pipe is usually quoted below Re of about 2,100 to 2,300 and fully turbulent above about 4,000, with an uncertain transition between; treat the thresholds as approximate.
Assumptions and limitations
- Liquid water only (0–100 °C at atmospheric pressure)
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for temperature to confirm this.
Frequently asked questions
What is viscosity at 20 °C?
Water at 20 °C has a dynamic viscosity of about 1.0 mPa·s.
Why does hot water flow more easily?
Weaker molecular attractions.
What is a centipoise?
A centipoise is 1 mPa·s (0.001 Pa·s), roughly the viscosity of water at 20 °C.
What does the Water Viscosity Calculator calculate?
Dynamic viscosity of liquid water at a temperature. It returns Dynamic viscosity and Typical accuracy.
What formula does the Water Viscosity Calculator use?
μ = 2.414×10⁻⁵ × 10^(247.8 ÷ (T − 140)) Pa·s, T in kelvin. Vogel-type correlation, accurate to about 2.5% between 0 and 100 °C.
What do I need to enter in the water Viscosity Calculator?
You enter Temperature (°C).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Liquid water only (0–100 °C at atmospheric pressure).
What is an example of a water Viscosity result?
With temperature 0, the dynamic viscosity is 1.7531 mPa·s.
Where does the method come from?
The method follows: Vogel–Fulcher–Tammann correlation for water (e.g. CRC Handbook of Chemistry and Physics, viscosity of water).
Related calculators
- Viscosity Calculator — Convert between dynamic viscosity (cP) and kinematic viscosity (cSt).
- Water Velocity Calculator — Water velocity in a pipe from flow and inside diameter.
- Reynolds Number Calculator — Reynolds number and flow regime in a pipe.
- Flow Rate Calculator — Volumetric flow rate from area and velocity, or volume and time.
- Specific Gravity Calculator — Specific gravity from density, relative to water at 1,000 kg/m³.
- Pressure Calculator — Pressure from force and area, with unit conversions.
Sources
- Vogel–Fulcher–Tammann correlation for water (e.g. CRC Handbook of Chemistry and Physics, viscosity of water)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.