Branch Count per Ton Calculator
Typical number of branch runs per ton of AC.
Enter your values
ⓘ Live results
Results
- Total system CFM
- 1,200 CFM
- Estimated branch runs
- 10.9
- Branches per ton
- 3.6
Quick answer
At roughly 400 CFM per ton and 100-150 CFM per branch, most residential systems need about 3-4 branch runs per ton.
Branches = (tons x 400) / CFM per branch
How to use the Branch Count per Ton Calculator
- 1Enter the equipment tonnage to get total system CFM at 400 CFM per ton.
- 2Choose a typical CFM per branch, commonly 100-150 CFM for bedrooms and small rooms.
- 3Divide to estimate how many branch takeoffs the trunk should have.
Worked example
Using the values the calculator loads with:
Inputs
- System size3 tons
- CFM per branch110 CFM
Results
- Total system CFM1,200 CFM
- Estimated branch runs10.9
- Branches per ton3.6
Frequently asked questions
Why does this vary by house?
Room count, sizes and loads all change how CFM is actually split, so this is only a planning estimate.
What about large rooms needing 2 branches?
Add those rooms' extra branch to the total; this calculator gives an average estimate, not a room-by-room design.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.