Manual D Friction Rate Calculator
Duct friction rate is pressure loss per length. Use it after airflow and duct size are known, then compare the run loss with the available static pressure budget.
friction rate calculator manual d manual d friction rate calculator duct friction rate calculator
Straight-run friction rate
dp / L = f * (rho * v^2 / 2) / Dh
Total equivalent length
dp_total = friction rate * TEL
Static budget
Run friction is only one part of Manual D-style design. Filters, coils, terminals and accessories still need to be added to the blower budget.
Related pages
- Duct size calculator - round and rectangular duct sizing from airflow.
- Duct friction loss calculator - run-level pressure loss from duct size and length.
- HVAC static pressure calculator - total external static pressure and blower margin.
- Grille size calculator - face velocity and free-area checks for terminals.