Fan CFM Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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Fluid calculations are especially sensitive to density, viscosity, geometry, pressure conventions, and unit systems. Fan CFM Calculator narrows that problem to the relationship used on this page, making the displayed air power easier to audit against the inputs and the governing equation.

What this calculator does

The Fan CFM Calculator uses Power output, Pressure, Mass air flow in CFM to estimate the page’s Air power from the fluid-mechanics relationship below. It is meant for a defined geometry and property set, so the useful part is not just the headline number but also whether your density, viscosity, dimensions, pressure reference, and flow convention match the model.

How to use it

Start with the fields that actually drive this result: Power output, Pressure, Mass air flow in CFM. Keep units consistent with the menus beside the fields and avoid mixing values measured under different conditions. After calculating, change one input at a time if you are comparing scenarios; that makes cause-and-effect much easier to see.

How the calculation works

The page converts volumetric flow to SI flow rate and calculates fluid/air power as Pair = Δp·Q. When an electrical or shaft power value is entered, it can compare that input with the useful fluid-power requirement.

Example

Using the page’s default example (Power output = 100 W; Pressure = 100 Pa; Mass air flow in CFM = 100 CFM), the calculator reports Air power of 4.719474 W. Change one driving input at a time and confirm the result moves in the direction predicted by the equation; that is a quick way to catch a unit or mode mistake.

How to interpret the result

Interpret the Air power within the fluid, geometry, pressure reference, and property values you entered. A numerically plausible answer can still be physically wrong if gauge/absolute pressure, diameter/radius, viscosity type, or unit convention is mismatched, so compare the result with the assumptions as well as the formula.

Limitations and notes

The voltage field and visible efficiency field do not independently drive the current headline; fluid power comes from flow and pressure, with efficiency inferred when an input-power value is supplied. Fan curves, system curves, density correction, motor efficiency, and stall are not modeled.