HVAC Duct Sizing for 500 Sq Ft Home
Complete duct sizing guide for a 500 square foot home. See recommended trunk and branch duct sizes, total CFM, BTU load, and tonnage requirements.
System Overview
Total CFM
500
Cooling Load
12,500 BTU
System Size
1.0 Ton
Main Trunk
12"
Branch Ducts
8"
Est. Rooms
3
Recommended Duct Layout
For a 500 square foot home, the HVAC system needs to deliver approximately 500 CFM of total airflow. This requires a 1.0 ton cooling system with a cooling capacity of 12,500 BTU per hour.
| Duct Section | Size | CFM | Notes |
|---|---|---|---|
| Main Supply Trunk | 12" round | 500 CFM | Sheet metal recommended |
| Branch Supply Runs | 8" round | 167 CFM each | Metal or flex acceptable |
| Main Return | 14" round | 500 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.