Airflow is a key performance metric for DC computer fans, as it determines the amount of cooling air that can be delivered to the computer components. The airflow of a DC computer fan is typically measured in cubic feet per minute (CFM) or cubic meters per hour (m³/h). Calculating the airflow accurately involves considering several factors.

The first factor is the fan's blade design. The shape, pitch, and number of blades all affect the amount of air the fan can move. Blades with a higher pitch can displace more air with each rotation, but they also require more power to drive. A fan with a larger number of blades may be able to move air more smoothly, but it can also create more air resistance, potentially reducing the overall airflow if not designed properly.

The rotational speed of the fan is another crucial element in airflow calculation. The faster the fan rotates, the more air it can move in a given time. However, the relationship between speed and airflow is not always linear. As the fan speed increases, the air resistance also increases, which can limit the effectiveness of further speed increases. For example, doubling the fan speed may not double the airflow due to the increased air resistance.

The fan's size also has a significant impact on airflow. Larger fans generally have a greater potential to move more air. A 120 - millimeter fan, for instance, can typically move more air than a 80 - millimeter fan, all other factors being equal. This is because the larger fan has a larger swept area, allowing it to displace more air with each rotation.

In addition to these factors, the design of the computer case and the placement of the fan within the case can also affect the actual airflow. Obstructions in the case, such as cables or other components, can disrupt the air flow and reduce the effectiveness of the fan. To calculate the airflow accurately, manufacturers often use computational fluid dynamics (CFD) simulations or perform physical tests in a controlled environment. These methods help in determining the optimal fan design and placement to achieve the desired airflow for effective cooling of computer components.