Viscosity Calculator

This application calculates the theoretical density (g/mL) and viscosity (cP) using the composition
of the mobile phase of your HPLC tubing (scale ACN/water), the temperature (C) of the tubing and the pressure (bar) of the system.


In order to better predict the pressure of HPLC tubing, it is important to take viscosity due to pressure into
account. Because the equation is itself dependent on pressure, it may require that you run the calculations a few times
to get the most accurate viscosity and, subsequently, pressure values. This combined with the complicated equation
required to calculate viscosity make the use of a calculator like this one a valuable time-saver making predictions
for HPLC operation.


To determine the viscosity and density of your tubing, input values into the fields as follows:

Composition should be a number between 0 and 1, and should be a ratio of ACN to water

Temperature should be a number between 20 and 80 and should be temperature of the system in degrees Celcius

Pressure should be a number between 0 and 1000, and should be the pressure of the system in bar

Once all fields in the input section of the page are filled, click the "Submit" button to start the calculation
The density and viscosity should appear in the labelled fields in the "Output" section of the calculator.
Density is calculated in grams per milliliter (g/mL) and viscosity is calculated with the units centiPoise (cP)

To clear all of the fields in the calculator, click the "Clear" button. The calculator does not require that
you clear all fields before every calculation, but the Clear button will remove values from all fields in the
"Input" and "Output" sections of the calculator



Before the desired calculations could be made, the input temperature was converted from degrees Celcius to Kelvin

Determining Density and Viscosity

Density is calculated using the following equation:

ρ = A1P2 + A2P + A3 + (B1P2 + B2P + B3)Φ + (C1P2 + C2P + C3)T + (D1P2 + D2P + D32 +(E1P2 + E2P + E3)ΦT + (F1P2 + F2P + F3)T2

In this equation,

P = pressure in bar

T = temperature in K

Φ = volume fraction of ACN on 0-1 scale

1 -8.84*10-8 5.06*10-8 4.98*10-10 -1.57*10-8 -1.63*10-10 -7.29*10-13
2 1.15*10-4 -1.75*10-4 -3.18*10-7 2.75*10-5 6.07*10-7 2.66*10-10
3 9.63*10-1 1.96*10-2 7.17*10-4 -5.57*10-2 -6.37*10-4 -1.95*10-6

Viscosity is calculated using the following equation:

ln(η) = A1P2+A2P + A3 + (B1P2+B2P + B3)Φ + (C1P2+C2P + C3)T + (D1P2+D2P + D32 + (E1P2+E2P + E3)ΦT + (F1P2+F2P + F3)T2 + (G1P2+G2P + G33 +(H1P2+H2P + H32T + (I1P2+I2P + I3)ΦT2

1 4.82*10-7 -7.41*10-7 -2.77*10-9 1.04*10-6 2.54*10-9 4.00*10-12 -4.57*10-7 -1.10*10-9 -4.05*10-12
2 -2.17*10-3 4.44*10-3 1.19*10-5 -2.01*10-3 -1.91*10-5 -1.59*10-8 6.43*10-4 3.37*10-6 2.38*10-8
3 1.64*10-1 -6.20*10 -8.81*10-2 -5.88*10 4.57*10-2 1.10*10-4 3.92*10-1 1.24*10-2 -7.43*10-5

The values were then sent to the corresponding fields in the Output section of the calculator


Many of the calculations for this tool were taken from the Pressure Prediction Calculator
that is also a part of the toolkit in

If you have any questions, comments or concerns, please contact Dr. Dwight Stoll at multidlc(at) or


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