ToolnozaENGINEERING TOOL
Duct Size Calculator
Size round and rectangular air ducts from airflow and target velocity, with CFM or m³/h inputs.
Duct Size Calculator
FREE ONLINE TOOLSTEP BY STEP
How to use duct size calculator
- Check the input units and assumptions.
- Review the result and example.
IN PRACTICE
Example
1000 m³/h at 5 m/s: A = 0.05556 m², round diameter = 265.96 mm.
GOOD TO KNOW
Which formula and assumptions are used?
A = Q / v; D = √(4A / π); h = A / w. Velocity-based sizing, not equal-friction design. Rectangular width is entered by the user; no noise, pressure-loss or fan-selection calculation.