Dynamic viscosity μ
Resistance to shear expressed in Pa·s, mPa·s, cP, P, or an equivalent unit.
Unit Converters
Viscosity Reference Table Calculator
For lubricant, coating, and fluid-property work, convert one dynamic-viscosity value across pascal-seconds, centipoise, poise, and customary units, then derive kinematic viscosity from a density stated at the same condition. The table keeps dynamic and kinematic viscosity in separate columns and units.
Dynamic viscosity—
Dynamic viscosity—
Density basis—
Kinematic viscosity—
Kinematic viscosity—
Kinematic viscosity—
Calculation ledgerUnrounded values drive all decisions
| Dynamic unit | Equivalent value | SI factor | Quantity type |
|---|
How to use
Convert dynamic viscosity and bridge to kinematic viscosity only with matching density
The reference table preserves the measured dynamic-viscosity quantity across equivalent units. Density then creates a separate kinematic-viscosity result. Do not use the bridge unless viscosity and density describe the same fluid, temperature, pressure, phase, and composition.
- Confirm the reported quantity is dynamic viscosity, not kinematic viscosity.
- Enter the value and exact source unit from the test record.
- Record the test temperature, pressure, method, and shear condition outside the numeric field.
- Enter density only when it is measured or sourced at the matching fluid condition.
- Report the original dynamic result first and label the density-derived kinematic result separately.
Viscosity-reference fundamentals
Kinematic viscosity ν
Dynamic viscosity divided by density, commonly expressed in m²/s or cSt.
Density bridge
Property relationship ν = μ/ρ at one matching condition.
Temperature dependence
Liquid viscosity can change sharply with temperature.
Unit equivalence
1 cP equals 1 mPa·s; conversion changes notation, not the fluid.
Result interpretation
Keep converted values separate from derived values
The dynamic table contains exact equivalents of the entered measurand. The kinematic cards are derived through the entered density and inherit its condition and uncertainty. A close match to a typical-fluid region is orientation, not identification or conformance.
Property method
Normalize μ to Pa·s before applying the density bridge
Every dynamic unit is converted through Pa·s. Kinematic viscosity is then μ/ρ in m²/s and converted to cSt or St.
Condition matching
Density at 15°C must not be combined casually with viscosity at 40°C.
Dynamic versus kinematic specifications
A cP limit and a cSt limit describe different quantities and cannot be compared directly.
Non-Newtonian materials
One viscosity value may be incomplete when shear rate, spindle, or time dependence defines the result.
Temperature control
Attach temperature to both μ and ρ
Condition mismatch can dominate the arithmetic conversion for many liquids.
Method control
Preserve how the viscosity was produced
Capillary timing, spindle and speed, shear history, and sample preparation can define different measurands.
Density quality
Do not use generic density when composition varies
Mixtures, temperature gradients, entrained gas, and concentration changes can invalidate the derived kinematic result.
Quantity identity
Keep μ and ν labels visible
Dynamic and kinematic values have different dimensions and specification meanings even when numbers look similar.
Rheology boundary
Use a curve when one number cannot describe the material
Shear-thinning, thixotropic, viscoelastic, or yield-stress materials require method-specific rheology.
Visual explanation
Read the logarithmic ladder before crossing the density bridge
The marker locates dynamic viscosity across orders of magnitude. The separately labeled arrow through density leads to kinematic viscosity; it is not another unit-only conversion.
Detailed calculation process
μPa·s = μsource × Fsource; νm²/s = μPa·s ÷ ρ; νcSt = νm²/s × 10⁶
| Symbol | Meaning | Unit |
|---|---|---|
| μ | dynamic viscosity | Pa·s |
| Fsource | source-to-Pa·s factor | Pa·s per source unit |
| ρ | matching density | kg/m³ |
| ν | derived kinematic viscosity | m²/s |
| νcSt | kinematic viscosity | cSt |
Property check:
Default input and assumption register
Keep the measured property separate from the density-derived property
The defaults describe a dynamic-viscosity result of 100 cP and a same-condition density of 850 kg/m³. Density is used only to derive kinematic viscosity; it does not alter the original dynamic measurement.
| Input | Default | Role | Evidence required |
|---|---|---|---|
| Dynamic viscosity | 100 cP | primary measured quantity | method result and unit |
| Density | 850 kg/m³ | dynamic-to-kinematic bridge | same sample condition |
| Temperature | not modeled | condition qualifier | report with both properties |
| Fluid behavior | one reported value | reference conversion | method and shear condition |
Secondary decision analysis
Audit the dynamic and kinematic tracks without mixing their meanings
The live register follows the value through the pascal-second bridge, the selected density, and the square-metre-per-second conversion. It keeps measured and derived quantities visibly distinct so a density assumption cannot be mistaken for a direct rheometer observation.
| Quantity | Current value | Derivation | Decision meaning |
|---|
Source evidence
Record the material state behind every reference value
Retain sample identity, test method, instrument, temperature, pressure, shear rate or spindle and speed, elapsed conditioning time, dynamic-viscosity unit, density method, and density temperature. If density comes from a handbook rather than the tested sample, label it as an external estimate and preserve the source revision.
Limitations and consequences
Do not use a unit bridge as a temperature or rheology model
The page does not correct viscosity between temperatures, predict pressure dependence, fit non-Newtonian behavior, reconcile different methods, or calculate measurement uncertainty. For shear-dependent fluids a single dynamic value may apply only to the stated shear condition; derived kinematic viscosity inherits that restriction and the uncertainty of density.
Viscosity-reference glossary
Dynamic viscosityShear stress divided by shear rate for the stated behavior.
Kinematic viscosityDynamic viscosity divided by density.
CentipoiseDynamic unit equal to one mPa·s.
CentistokeKinematic unit equal to one mm²/s.
Newtonian fluidFluid with viscosity independent of shear rate under stated conditions.
Density bridgeCondition-dependent conversion between μ and ν.
Additional viscosity-reference terminology
Condition matchingUse of viscosity and density values for the same material state, especially the same temperature and pressure.
Rheological modelRelationship between shear stress and shear rate required when viscosity is not constant with test condition.
Practical reference cases
Lubricant data reconciliation
A cP laboratory result is converted to Pa·s, then paired with density at the same 40°C condition to derive cSt.
Coating specification
The analyst stops because the document lists cSt while the test report gives spindle-based cP without a matching density or shear condition.
A viscosity number without condition is incomplete
Temperature and method can change the measurand more than the unit conversion; keep them attached to every reported value.
Viscosity reference FAQ
Is cP the same as mPa·s?
Yes, numerically and dimensionally.
Is cSt the same quantity as cP?
No. cSt is kinematic viscosity; cP is dynamic viscosity.
Why is density required?
It links dynamic and kinematic viscosity through ν = μ/ρ.
Can I use density at another temperature?
Not for a controlled property conversion.
Does the ladder identify my fluid?
No; it only locates magnitude.
Does conversion correct for temperature?
No. Unit conversion preserves the entered material condition and applies no temperature relationship.
Can I convert non-Newtonian viscosity?
Only the unit; interpretation still requires shear and method context.
Is density uncertainty included?
No. Density uncertainty must be evaluated separately when it materially affects the derived kinematic result.
Which result should be reported first?
Report the measured dynamic value before the derived kinematic value.
Advanced viscosity-reference questions
May handbook density be used?
Only as a clearly labeled estimate when its material composition, temperature, and pressure are compatible. A measured sample density is preferable whenever kinematic viscosity supports a controlled or release decision. Retain the density method, temperature, pressure, and composition match because the derived kinematic result inherits every density assumption.
Does the conversion work for a non-Newtonian fluid?
The units still convert, but one reported dynamic viscosity is not a complete material description. Preserve the test geometry, shear rate, time dependence, and rheological model before comparing the result. Preserve geometry, shear rate, timing, and conditioning for non-Newtonian materials so the converted number retains its measurand definition.
Why do cP and mPa·s have the same numerical value?
One centipoise is exactly one millipascal-second. The equality is a unit identity for dynamic viscosity and does not imply equality with centistokes, which is kinematic viscosity. Keep dynamic and kinematic units explicitly labeled in every export; equal-looking prefixes do not make cP and cSt interchangeable.
Can viscosity at one temperature be converted to another?
Not with unit factors or density alone. A validated material-specific temperature relationship and supporting measurements are required; the calculator intentionally does not invent one. Attach the validated material-specific relationship before reporting a temperature-adjusted value, including its fitted range and uncertainty.
Which result should be reported as measured?
Report the original dynamic-viscosity result, method, unit, and condition as measured. Report kinematic viscosity separately as derived, together with the density value and source used. Identify the dynamic value as measured and the kinematic value as derived, with the density source beside the latter in the final record.