Calculator inputs
Choose a mode, enter values, and select output units. The calculator validates every submitted value before processing.
Formula used
Dynamic viscosity: μ = ν × ρ
Density: ρ = μ ÷ ν
Reynolds number: Re = V × D ÷ ν
Kinematic viscosity measures momentum diffusion relative to fluid density. One centistoke equals one square millimetre per second. Temperature strongly changes liquid water viscosity.
Temperature comparison table
The table follows the chart temperature range and interval.
| Temperature, °C | Density, kg/m³ | Dynamic viscosity, mPa·s | Kinematic viscosity, m²/s | Kinematic viscosity, cSt |
|---|---|---|---|---|
| 0.000 | 999.8676 | 1.753058 | 1.75328992e-6 | 1.753290 |
| 10.000 | 999.7281 | 1.299537 | 1.29989031e-6 | 1.299890 |
| 20.000 | 998.2336 | 1.001749 | 1.00352134e-6 | 1.003521 |
| 30.000 | 995.6783 | 0.797232 | 8.00692799e-7 | 0.800693 |
| 40.000 | 992.2473 | 0.651428 | 6.56517657e-7 | 0.656518 |
| 50.000 | 988.0633 | 0.544160 | 5.50733927e-7 | 0.550734 |
| 60.000 | 983.2106 | 0.463103 | 4.71011396e-7 | 0.471011 |
| 70.000 | 977.7491 | 0.400429 | 4.09541741e-7 | 0.409542 |
| 80.000 | 971.7224 | 0.350993 | 3.61207373e-7 | 0.361207 |
| 90.000 | 965.1633 | 0.311316 | 3.22552393e-7 | 0.322552 |
| 100.000 | 958.0966 | 0.278980 | 2.91181003e-7 | 0.291181 |
Interactive water-property chart
Switch datasets, change scale, or download the chart image.
Batch temperature calculations
These values use the selected temperature and pressure units.
| Entered temperature, °C | Temperature, °C | Density, kg/m³ | Dynamic viscosity, mPa·s | Kinematic viscosity, cSt |
|---|---|---|---|---|
| 0.0000 | 0.0000 | 999.8676 | 1.753058 | 1.753290 |
| 20.0000 | 20.0000 | 998.2336 | 1.001749 | 1.003521 |
| 40.0000 | 40.0000 | 992.2473 | 0.651428 | 0.656518 |
| 60.0000 | 60.0000 | 983.2106 | 0.463103 | 0.471011 |
| 80.0000 | 80.0000 | 971.7224 | 0.350993 | 0.361207 |
| 100.0000 | 100.0000 | 958.0966 | 0.278980 | 0.291181 |
How to use this calculator
- Select the calculation mode matching your available data.
- Enter temperature, pressure, viscosity, density, or conversion values.
- Choose units and the required result precision.
- Add optional flow, comparison, target, or batch values.
- Select Calculate and review the result above.
- Copy, print, or export the completed calculation.
Understanding kinematic viscosity
Kinematic viscosity compares internal flow resistance against fluid density. Lower values usually indicate easier momentum movement through water. Engineers use it for Reynolds number and pipe calculations.
Dynamic versus kinematic viscosity
Dynamic viscosity measures resistance to shearing motion inside water. Kinematic viscosity also accounts for the water density. Their relationship is expressed by ν = μ ÷ ρ.
Temperature and pressure effects
Water viscosity falls significantly as temperature rises. Density changes more gradually across ordinary liquid temperatures. Pressure corrections remain approximate in this general engineering calculator.
Units and conversions
The SI unit is square metres per second. Engineers often use centistokes for convenient water values. One cSt always equals one mm²/s exactly.
Limitations and accuracy
This tool estimates pure liquid water properties. Saltwater, wastewater, and chemical mixtures need separate property models. Verify critical designs against approved engineering standards and datasets.
Example data
| Example | Typical input | Purpose |
|---|---|---|
| Cold water | 5°C and 1 atm | Estimate high liquid viscosity |
| Room-temperature water | 20°C and 1 atm | General engineering reference |
| Warm water | 40°C and 1 atm | Compare temperature effects |
| Hot water | 80°C and 1 atm | Estimate lower viscosity |
| Near-boiling water | 95°C and 1 atm | Check phase warnings |
| Direct calculation | 1.002 mPa·s and 998.2 kg/m³ | Calculate ν from μ and ρ |
| Custom density | 0.89 cSt and 995 kg/m³ | Calculate dynamic viscosity |
| Unit conversion | 1.004 cSt | Convert into SI or imperial units |
Frequently asked questions
What is the kinematic viscosity of water?
It changes with temperature and pressure. Near 20°C, water is approximately one centistoke. Always use conditions matching the intended calculation.
What is the difference between dynamic and kinematic viscosity?
Dynamic viscosity measures shear resistance. Kinematic viscosity divides that resistance by density. Both values describe different aspects of fluid motion.
How does temperature affect water viscosity?
Higher temperatures reduce liquid water viscosity. Molecules move more freely as thermal energy rises. The effect is important in flow calculations.
What is the kinematic viscosity formula?
Use ν = μ ÷ ρ. Enter consistent units before dividing the values. This calculator converts every supported unit automatically.
Is mm²/s equal to centistokes?
Yes, one mm²/s equals one cSt. The numerical values are therefore identical. Only the displayed unit name changes.
Does water pressure affect viscosity?
Pressure can affect viscosity and density. The effect is modest near atmospheric conditions. High-pressure engineering requires specialized property formulations.
Why is water density required?
Density connects dynamic and kinematic viscosity. Without density, direct conversion between them is impossible. Temperature mode estimates density automatically.
Can this calculator be used for saltwater?
The automatic model represents pure water. Salt changes density and viscosity significantly. Use measured properties through the manual modes.
Which viscosity unit should engineers use?
Use m²/s for strict SI work. Centistokes are convenient for common liquid values. Follow the project standard whenever one exists.