Convert between flow units and check the resulting pipe velocity in one step. Enter any flow rate, pick the unit, and set the pipe bore. The tool returns the equivalent flow in every common unit, the mean velocity, and whether that velocity sits inside the usual design range for your fluid.
Velocity is the mean velocity, calculated as flow divided by internal cross-section. Real profiles are not uniform, so the peak velocity at the pipe centre is typically 1.2 to 1.3 times this figure. For gas, enter the flow at actual conditions, not standard conditions.
How to use the result
Velocity is the number that decides most piping arguments. Two meters on the same flow in different pipe sizes are not interchangeable, because the velocity, the pressure drop and the straight run requirement all change with the bore.
A velocity that sits below the range usually means the pipe is oversized for the duty. That is not automatically wrong, but it costs money in steel and it makes some meter types unreliable at low flow. A velocity above the range means erosion, noise and vibration, and it will shorten the life of anything with a rotor in it.
Choosing a meter once you know the velocity
With flow and bore fixed, the meter choice usually narrows to two or three options. Our flow meter selection guide walks through the decision by fluid type. If the fluid conducts electricity, compare the electromagnetic flow meter against the clamp on ultrasonic flow meter. For gas and steam, start with the vortex flow meter range.
What this calculator does not do
It does not size a meter, and it does not calculate pressure drop. Those need the fluid density, viscosity and the meter’s own loss coefficient. Send us the flow, bore, pressure and temperature and we will do the sizing properly.