Viscosity Conversion Calculator
Convert between dynamic and kinematic viscosity units including cP, cSt, Pa·s, and Stokes. Enter values for instant results with step-by-step formulas.
Calculator
Adjust values & calculateDynamic Viscosity
Kinematic Viscosity
Formula
Where kinematic viscosity is in m2/s (or cSt), dynamic viscosity is in Pa.s (or cP), and density is in kg/m3 (or g/cm3). For cP to cSt conversion: cSt = cP / density(g/cm3). Dynamic viscosity measures resistance to flow under applied force; kinematic viscosity measures flow under gravity.
Last reviewed: December 2025
Worked Examples
Example 1: Motor Oil Viscosity Conversion
Example 2: Chemical Process Fluid Conversion
Background & Theory
The Viscosity Conversion Calculator applies the following established principles and formulas. Structural and construction engineering is governed by fundamental load analysis, material science, and regulatory standards that ensure the safety and durability of built structures. The primary distinction in load analysis is between dead loads — the permanent self-weight of structural elements, finishes, and fixed equipment — and live loads, which represent variable occupancy, furniture, and environmental forces such as wind and snow. These are combined using factored load equations, such as the ASCE 7 formula U = 1.2D + 1.6L, where D is dead load and L is live load. Concrete mix design is governed by the water-cement (w/c) ratio, which is the primary determinant of compressive strength and durability. A w/c ratio of 0.40–0.45 typically yields concrete with 28-day compressive strengths of 30–40 MPa. Common mix ratios by weight for structural concrete are approximately 1 part cement : 1.5–2 parts sand : 3 parts coarse aggregate. Structural steel is characterized by its yield strength (the stress at which permanent deformation begins, typically 250–350 MPa for mild steel) and ultimate tensile strength (typically 400–500 MPa). Mid-span deflection of a simply supported beam under a central point load is given by δ = FL³ / (48EI), where F is force, L is span length, E is Young's modulus, and I is the second moment of area. Building insulation is rated by R-value, a measure of thermal resistance in units of m²·K/W (SI) or ft²·°F·h/BTU (imperial). Higher R-values indicate greater resistance to heat flow. Foundation design depends on the allowable bearing capacity of the underlying soil, which ranges from approximately 75 kPa for soft clay to over 10,000 kPa for bedrock. Drainage gradients for surface water are typically specified as a minimum of 1–2% slope away from building foundations to prevent hydrostatic pressure and water infiltration.
History
The history behind the Viscosity Conversion Calculator traces back through the following developments. The history of construction engineering spans thousands of years of accumulated empirical knowledge and, more recently, rigorous scientific analysis. The ancient Egyptians built the Great Pyramid of Giza around 2560 BCE using an estimated 2.3 million stone blocks, demonstrating sophisticated logistics, geometry, and workforce organization. Roman engineers advanced the field dramatically through the use of pozzolanic concrete — a mixture of volcanic ash, lime, and seawater — enabling the construction of the Pantheon dome (43.3 m diameter, completed around 125 CE) and a vast network of aqueducts and roads across the empire. Cast iron emerged as a structural material during the Industrial Revolution, first used prominently in the Iron Bridge at Coalbrookdale, England, completed in 1779. Wrought iron and later steel allowed far greater spans and heights. The Eiffel Tower, completed in 1889, demonstrated the structural possibilities of wrought iron at scale and influenced the development of steel-frame skyscraper construction in Chicago and New York. Reinforced concrete was systematically developed by Joseph Monier, a French gardener, who patented iron-reinforced concrete pots and panels in the 1860s, and later by engineers including François Hennebique who created the first comprehensive reinforced concrete framing system in the 1890s. The 1906 San Francisco earthquake caused widespread devastation and galvanized the engineering profession to develop seismic design provisions. Subsequent earthquakes — including the 1971 San Fernando and 1994 Northridge events — drove successive improvements in seismic codes, base isolation technology, and ductile detailing of reinforced concrete and steel frames. Building codes became increasingly standardized in the twentieth century, with the International Building Code (IBC) first published in 2000 providing a unified model code adopted across much of the United States. Building Information Modeling (BIM) emerged in the 2000s as a digital workflow integrating architectural, structural, and MEP design into a unified three-dimensional model, fundamentally changing coordination practices across the industry.
Frequently Asked Questions
Formula
Kinematic Viscosity = Dynamic Viscosity / Density
Where kinematic viscosity is in m2/s (or cSt), dynamic viscosity is in Pa.s (or cP), and density is in kg/m3 (or g/cm3). For cP to cSt conversion: cSt = cP / density(g/cm3). Dynamic viscosity measures resistance to flow under applied force; kinematic viscosity measures flow under gravity.
Worked Examples
Example 1: Motor Oil Viscosity Conversion
Problem: An SAE 30 motor oil has a kinematic viscosity of 100 cSt at 40 degrees C and a density of 0.88 g/cm3. Convert to dynamic viscosity in cP, Pa.s, and SUS.
Solution: Dynamic viscosity = kinematic x density\ncP = 100 cSt x 0.88 g/cm3 = 88 cP\nPa.s = 88 / 1000 = 0.088 Pa.s\n\nSUS = 4.6324 x 100 + 1 + (3930.2 / 10000)\nSUS = 463.24 + 1 + 0.39 = 464.6 SUS
Result: 88 cP | 0.088 Pa.s | 464.6 SUS | 405.7 Redwood seconds
Example 2: Chemical Process Fluid Conversion
Problem: A process fluid has a dynamic viscosity of 25 cP and density of 1.15 g/cm3. Convert to kinematic viscosity in cSt, St, and m2/s.
Solution: Kinematic viscosity = dynamic / density\ncSt = 25 cP / 1.15 g/cm3 = 21.74 cSt\nSt = 21.74 / 100 = 0.2174 St\nm2/s = 21.74 x 10^-6 = 2.174 x 10^-5 m2/s\nmm2/s = 21.74 mm2/s (same as cSt)
Result: 21.74 cSt | 0.2174 St | 2.174e-5 m2/s
Frequently Asked Questions
What is the difference between dynamic and kinematic viscosity?
Dynamic viscosity (also called absolute viscosity) measures a fluid resistance to flow under an applied shear stress, expressed in units like Pascal-seconds (Pa.s) or centipoise (cP). It represents the internal friction within the fluid as layers slide past each other. Kinematic viscosity is dynamic viscosity divided by the fluid density, expressed in units like centistokes (cSt) or square meters per second (m2/s). Kinematic viscosity represents how quickly the fluid flows under the influence of gravity alone. The relationship is simply kinematic viscosity equals dynamic viscosity divided by density. Water at 20 degrees Celsius has a dynamic viscosity of about 1 cP and a kinematic viscosity of about 1 cSt because its density is approximately 1 g/cm3.
What is a centipoise and how does it relate to other viscosity units?
A centipoise (cP) is one hundredth of a poise, which is the CGS unit of dynamic viscosity. One centipoise equals one millipascal-second (mPa.s) in SI units, making conversions between these two units straightforward. To convert centipoise to pascal-seconds, divide by 1000 (so 1 cP equals 0.001 Pa.s). The centipoise is one of the most commonly used viscosity units in industry because water at 20 degrees Celsius has a viscosity of almost exactly 1 cP, providing an intuitive reference point. Common fluids measured in centipoise include motor oils (50 to 500 cP), honey (2,000 to 10,000 cP), ketchup (50,000 to 100,000 cP), and blood (approximately 3 to 4 cP).
How does temperature affect fluid viscosity?
Temperature has a dramatic effect on fluid viscosity, and the relationship differs between liquids and gases. For liquids, viscosity decreases significantly as temperature increases because thermal energy allows molecules to move past each other more easily. A typical motor oil might have a viscosity of 300 cSt at 40 degrees Celsius but only 10 cSt at 100 degrees Celsius, a 30-fold reduction. This temperature sensitivity is characterized by the viscosity index (VI), where a higher VI indicates less change with temperature. For gases, viscosity increases with temperature because faster-moving molecules transfer more momentum between fluid layers. The Andrade equation and Walther equation are commonly used to model liquid viscosity variation with temperature.
What viscosity units are used in different industries?
Different industries have traditionally used different viscosity units based on their measurement methods and historical conventions. The petroleum industry commonly uses centistokes (cSt) for kinematic viscosity and Saybolt Universal Seconds (SUS) for empirical measurements, with viscosity grades defined at 40 and 100 degrees Celsius. The chemical and pharmaceutical industries typically use centipoise (cP) or Pascal-seconds (Pa.s) for dynamic viscosity. The paint and coatings industry often uses Krebs Units (KU) or cup-type measurements like Ford Cup seconds or Zahn Cup seconds. The food industry may use Brabender Units or empirical consistometer readings. The lubricant industry uses ISO viscosity grades based on kinematic viscosity in cSt at 40 degrees Celsius.
What is the viscosity of common fluids at room temperature?
At approximately 20 to 25 degrees Celsius, common fluids span an enormous viscosity range. Air has a dynamic viscosity of about 0.018 cP. Water is approximately 1 cP, which serves as the standard reference. Milk is about 3 cP, blood is 3 to 4 cP, and olive oil ranges from 80 to 100 cP. SAE 10W motor oil is roughly 50 to 80 cP, while SAE 30 oil is 150 to 200 cP. Glycerin is about 1,500 cP, honey ranges from 2,000 to 10,000 cP depending on moisture content, and corn syrup is approximately 5,000 to 10,000 cP. Peanut butter can exceed 200,000 cP. Understanding these reference points helps engineers evaluate whether a calculated or measured viscosity value is reasonable.
How is viscosity measured in a laboratory setting?
Laboratory viscosity measurement uses several types of instruments depending on the fluid type and viscosity range. Capillary viscometers (like Ubbelohde or Cannon-Fenske types) measure kinematic viscosity by timing gravity-driven flow through a calibrated capillary tube and are ideal for Newtonian fluids in the 0.5 to 20,000 cSt range. Rotational viscometers (Brookfield type) measure dynamic viscosity by rotating a spindle in the fluid and measuring the torque resistance, suitable for both Newtonian and non-Newtonian fluids from 1 to several million cP. Falling ball viscometers time a sphere falling through the fluid. Cone-and-plate rheometers provide the most precise measurements and can characterize complex flow behavior including shear thinning and thickening effects.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy