Inputs

How to use it

Enter only the requested values and check the unit shown beside each field. The main result gives the figure to use first. Details explain conversions, secondary quantities and rounding. Change any value to compare another situation without starting again.

Before using the result

Check units, stated assumptions and manufacturer data. The result explains a conversion or provides a technical estimate; it does not by itself certify an installation or professional design.

Method and references

ASHRAE Handbook, Duct Design — Q = V × A

Scope and limits

Geometric calculation only; pressure loss, noise, roughness and fittings are excluded.