The viscosity of a fluid describes how easily it flows. Water has a low viscosity, it flows very easily, (it is very runny). Tomato ketchup has a higher viscosity than water, it does not flow very easily, (it seems “thicker” than water). The viscosity of some liquids is shown below.

Liquid Viscosity
Water 1
Milk 3.2
No. 4 fuel oil 12.6
Cream 16.5
Vegetable oil 34.6
SAE 10 oil 88
Tomato juice 176
SAE 30 oil 352
Glycerine 880
SAE 50 oil 1561
Honey 1760
Glue 3000
Mayonnaise 5000
Molasses B 8640
Sour cream 15,200
SAE 70 oil 17,640

The viscosity of liquids can be compared by timing how long it takes for a known volume of each liquid to flow through a hole.

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