How to Convert CFM to Tons of Refrigeration
CFM measures airflow, while tons of refrigeration measure cooling capacity. They are different quantities, so there is no universal conversion between them.
For a preliminary estimate, this calculator assumes 400 CFM per ton. Carrier identifies this as a common airflow target, while noting that the appropriate airflow varies by equipment and application. Carrier airflow guidance
Calculation Formula
Estimated Cooling Tons=400Airflow (CFM)
The denominator represents the assumed airflow requirement in CFM per ton. It is not a fixed physical conversion factor.
How to Use the CFM to Tons Calculator
- Enter the airflow: Provide the airflow value in cubic feet per minute.
- Review the result: The calculator divides the entered value by 400.
- Check the assumption: Compare the estimate with the equipment manufacturer’s specified airflow and cooling capacity.
Use airflow representing the system or section you are evaluating. One room’s supply airflow should not be mistaken for the entire system’s airflow.
Example Calculations
Example 1: Convert 1,200 CFM to Tons
Estimated Cooling Tons=4001200=3
At the assumed rate of 400 CFM per ton, 1,200 CFM corresponds to an estimated 3 tons of cooling capacity.
Example 2: Convert 800 CFM to Tons
Estimated Cooling Tons=400800=2
Using the same assumption, 800 CFM corresponds to an estimated 2 tons.
These results describe the relationship under the chosen assumption. They do not confirm the equipment’s actual cooling performance.
What Can This Calculator Help With?
- Understanding the approximate relationship between system airflow and cooling tonnage.
- Checking arithmetic against a 400 CFM-per-ton reference.
- Preparing questions about airflow and equipment ratings for an HVAC assessment.
It does not calculate a building’s cooling load, size ductwork, or select the correct air conditioner. Equipment sizing requires a heating and cooling load assessment. U.S. Department of Energy
Frequently Asked Questions
1. What does CFM mean?
CFM stands for cubic feet per minute. It describes the volume of air moving through a system each minute.
2. What is a ton of refrigeration?
A ton of refrigeration is a unit of cooling capacity equal to 12,000 BTU per hour. It does not describe the equipment’s physical weight. Carrier capacity reference
3. Is 400 CFM per ton correct for every system?
No. It is a useful reference assumption, not a universal requirement. The appropriate airflow depends on equipment specifications and the application’s temperature and humidity-control needs. Use the manufacturer’s performance data when evaluating a particular system.
4. How do I determine the CFM needed for my room?
Do not rely on a universal CFM-per-square-foot figure. Required supply airflow depends on the room’s heating and cooling loads and the system design. Ventilation and exhaust requirements are separate from cooling-airflow estimates.
5. Can this calculator be used to size a heating system?
Not using the 400 CFM-per-ton cooling assumption. Heating calculations require information about heat output and the intended air-temperature rise, along with the equipment specifications.
6. Does increasing CFM always increase cooling capacity?
No. More airflow does not automatically mean more cooling. Airflow must be appropriate for the equipment and its operating conditions; changing it can also affect humidity removal and comfort.
7. Why might my equipment’s rated tonnage differ from the result?
The equipment may operate at an airflow rate other than 400 CFM per ton. The entered CFM may also represent a nominal fan rating rather than actual installed airflow. Check the equipment data and measured system performance before drawing conclusions.
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