What is the formula to calculate the Reynolds number in circular tubes in terms of mass flow rate?

For circular tubes,

The Reynolds number in terms of mass flow rate is given by,

Re=4ṁ/(µ*pi*D) ........ [For circular tubes only]

where,

ṁ=mass flow rate, kg/s

µ=dynamic viscosity, Ns/m2

D=diameter of pipe, m