Bathroom Airflow Calculator

Learn how to calculate bathroom volume and determine the airflow needed for effective ventilation. Use the MMotors Bathroom Fan Calculator to find the right fan size and prevent humidity, mold, and condensation.

Fan size guide

Bathroom fan calculator

Select your approximate bathroom dimensions and we will recommend the airflow capacity you need.

Bathroom volume 0 m³
Recommended fan capacity 60 m³/h Based on 6 air changes per hour
Check our Ø100mm fans
Our 100 mm diameter models with airflow of 60, 105 and 169 m³/h
Formula: Volume = A × B × H, then airflow = volume × 6

Choosing the right bathroom fan airflow is essential for maintaining a healthy, moisture-free environment. Proper ventilation helps prevent condensation, mold growth, and unpleasant odors, especially in smaller or frequently used bathrooms. This bathroom airflow calculator is designed to give you a quick and reliable estimate based on your room size and the recommended 6 air changes per hour.

Keep in mind that the calculated result is a minimum guideline. In real-life conditions(such as longer duct runs, bends in ventilation pipes, or higher humidity levels) it is always better to choose a fan with slightly higher airflow capacity. A stronger fan will ensure more effective moisture removal and better long-term performance.

For example, if the calculator suggests 70 m³/h, it is recommended to choose a 100–105 m³/h fan instead of a 60 m³/h model. Similarly, if you get a result of around 108 m³/h, selecting a 169 m³/h fan will provide more efficient ventilation.

When in doubt, always round up rather than down. A higher airflow bathroom fan improves air quality, reduces the risk of mold, and keeps your space fresh and comfortable.