Duct Traverse CFM Calculator
Actual airflow from an averaged pitot/anemometer traverse of a duct.
Use the log-Tchebycheff grid (min 25 points rectangular) and traverse ≥ 7.5 diameters downstream of fittings — single-point centre readings overstate flow 10–15%.
Formula
Duct Traverse CFM Calculator is a free duct traverse for HVAC designers, technicians and energy auditors — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Duct Traverse CFM Calculator
Actual airflow from an averaged pitot/anemometer traverse of a duct. The calculation implements Q = V_avg × A_duct (ISO 3966 / ASHRAE 111 — airflow measurement). Use the log-Tchebycheff grid (min 25 points rectangular) and traverse ≥ 7.5 diameters downstream of fittings — single-point centre readings overstate flow 10–15%.
How to use Duct Traverse CFM Calculator
- 1Enter Average measured velocity in m/s.
- 2Enter Duct width (or Ø for round) in mm.
- 3Enter Duct height (0 for round) in mm.
- 4Read Airflow, Airflow instantly — no submit button needed.
- 5Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Duct Traverse CFM Calculator?
- ✓Implements the standard formula — Q = V_avg × A_duct
- ✓Reference cited on-page: ISO 3966 / ASHRAE 111 — airflow measurement
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Duct Traverse CFM Calculator use?+
It computes Q = V_avg × A_duct, per ISO 3966 / ASHRAE 111 — airflow measurement. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Use the log-Tchebycheff grid (min 25 points rectangular) and traverse ≥ 7.5 diameters downstream of fittings — single-point centre readings overstate flow 10–15%.
Is this based on ASHRAE methods?+
The calculations follow the standard ASHRAE/ISHRAE formulations cited under the result, simplified where industry practice does the same. For permit-grade design, confirm with the full code procedure.
Is the Duct Traverse CFM Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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