# What is CFM?

Cubic Feet per Minute (CFM) is the standard measurement of airflow. A typical air conditioning system produces 400 CFM per ton of air conditioning.

The higher the CFM, the more cooling power the system has. It’s important to have an accurate CFM when selecting an air conditioner, as too little or too much CFM can lead to inefficient cooling and even premature system failure.

The CFM rating of a product can be determined by multiplying the airflow in cubic feet per minute by the static pressure in inches of water.

## What is SCFM?

Static pressure is the resistance to airflow that is created by obstructions in the ducts or filters. SCFM stands for “standard cubic feet per minute” and is used to compare the airflow of different products.

## Which is better CFM or SCFM?

SCFM is a metric based on standard conditions, so it’s universally used. CFM is the more commonly used measurement in the United States, since most airflow measurements are made in inches of water. When comparing two products with different airflow ratings, use SCFM to make an apples-to-apples comparison.

## How much CFM is needed for a room?

A good rule of thumb is that the mininum should be 1 CFM per square foot. This will give you the minimum CFM needed for the room.

A basic calculation for those planning on becoming an HVAC professional is:

- CFM = (fpm * area), where fpm is the feet per minute.
- To find the cubic feet per minute, substitute the FPM value with the area after the area is squared.

## Related Links

Use the Air Changes Calculation to Determine Room CFM

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