Round ↔ Rectangular Duct Converter

Convert between round duct diameter and rectangular duct dimensions using practical equivalent sizing.

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Frequently asked questions

What does a round to rectangular duct converter do?

It estimates an equivalent rectangular duct size for a round duct, or an equivalent round diameter for a rectangular duct, to help with HVAC layout and retrofit planning.

Does equivalent duct size guarantee the same airflow?

No. Equivalent size is only a starting point. Final airflow performance still depends on friction rate, velocity, fitting losses, and system layout.

When should I use a duct size converter?

Use it when field conditions require changing duct shape, such as converting between round and rectangular duct in tight spaces or retrofit situations.

Is this a full duct design calculator?

No. This tool gives a practical equivalent size estimate. Final duct design should still be checked with friction rate, velocity, effective length, and overall system requirements.

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