HVAC Duct Sizing for 4,000 Sq Ft Home
Complete duct sizing guide for a 4,000 square foot home. See recommended trunk and branch duct sizes, total CFM, BTU load, and tonnage requirements.
System Overview
Recommended Duct Layout
For a 4,000 square foot home, the HVAC system needs to deliver approximately 4,000 CFM of total airflow. This requires a 8.3 ton cooling system with a cooling capacity of 100,000 BTU per hour.
| Duct Section | Size | CFM | Notes |
|---|---|---|---|
| Main Supply Trunk | 34" round | 4000 CFM | Sheet metal recommended |
| Branch Supply Runs | 8" round | 200 CFM each | Metal or flex acceptable |
| Main Return | 36" round | 4000 CFM | Larger for lower velocity |
Important Notes
These are general estimates based on 1 CFM per square foot and 25 BTU per square foot. Actual requirements vary based on climate zone, insulation quality, window area, ceiling height, and occupancy. For accurate sizing, a Manual J load calculation and Manual D duct design should be performed by a licensed HVAC professional.
Related Guides
Other Home Sizes
Compare Top HVAC Equipment, Duct Supplies & Local Contractor Deals
Looking for ductwork materials, flexible duct bundles, airflow diagnostic meters, or contractor quotes? Browse current specials.