Branch Count per Ton Calculator
Typical number of branch runs per ton of AC.
Enter your values
Enter the system size in tons.
Enter the cfm per branch in CFM.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- 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
At a glance
| What it does | Typical number of branch runs per ton of AC. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | System size, CFM per branch |
| Main output | Total system CFM |
| Formula | Branches = (tons x 400) / CFM per branch |
| Cost | Free — no sign-up, no download |
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.
Inputs explained
- System size(tons)
- Enter the system size in tons.
- CFM per branch(CFM)
- Enter the cfm per branch in CFM.
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.
What do I need to enter into the Branch Count per Ton Calculator?
Just 2 values: system size, cfm per branch. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Branch Count per Ton Calculator work out the answer?
At roughly 400 CFM per ton and 100-150 CFM per branch, most residential systems need about 3-4 branch runs per ton. It applies the formula Branches = (tons x 400) / CFM per branch and shows the working so you can check each step by hand.
Is the Branch Count per Ton Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.