Free Reynolds number calculator with preset fluid properties. Classify laminar, transitional and turbulent flow for pipes, flat plates and spheres. Includes engineering notes for each regime.
Reynolds number is probably the most used dimensionless number in fluid mechanics. Everyone knows the formula, Re = VD/nu, but you still need to look up kinematic viscosity for your fluid every time you want to classify flow. And then you need to remember whether the transition number is 2300 or 2000 or 4000 depending on which textbook you are using.
I built this with preset properties for common fluids so you do not have to look up nu every time. It also handles flat plate and sphere geometry in addition to pipe flow, since the transition Reynolds numbers are different for each. The engineering notes at the bottom tell you what the flow classification actually means for your calculation, which is more useful than just showing a number.