12 Inch Duct Calculator
Calculate airflow capacity for 12 inch round ductwork. See CFM ratings at different velocities, recommended applications, and friction loss data for 12" HVAC ducts.
Airflow Capacity for 12" Round Duct
A 12 inch round duct has a cross sectional area of 113.1 square inches (0.785 sq ft). The table below shows the CFM airflow at different air velocities.
| Velocity (FPM) | Airflow (CFM) | Noise Level | Use Case |
|---|---|---|---|
| 600 FPM | 471 CFM | ✅ Quiet | Residential supply |
| 700 FPM | 550 CFM | ✅ Quiet | Residential supply |
| 800 FPM | 628 CFM | ⚠️ Moderate | Commercial supply |
| 900 FPM | 707 CFM | 🔊 May be noisy | Industrial |
Recommended Applications
Living rooms, master bedrooms, main trunk branches
At the standard residential friction rate of 0.08 in/wg per 100 feet, a 12 inch duct is ideal for delivering 550 CFM at a quiet 700 FPM velocity.
Quick Duct Sizing Formula
CFM for 12" Duct
CFM = (π/4) × (12/12)² × Velocity At 700 FPM: CFM = 0.7854 × 700 = 550 CFM