Viscometer
![Ostwald viscometers measure the viscosity of a fluid with a known density.](/Images/godic/202502/20/Ostwaldscher_Zähigkeitsmesser1450.jpg")
![Creeping flow past a sphere.](/Images/godic/202502/20/Terminal_velocity.svg1450.png")
![](/Images/godic/202502/20/OPvisc11450.JPG")
![Measuring Principle of the Electromagnetically Spinning Sphere Viscometer](/Images/godic/202502/20/EMS_viscometer_measuring_principle1450.png")
A viscometer (also called viscosimeter) is an instrument used to measure the viscosity of a fluid. For liquids with viscosities which vary with flow conditions, an instrument called a rheometer is used. Viscometers only measure under one flow condition.