Area is determined by multiplying length and width (in feet). Using the input fields in Step 1, the calculator will determine area (in square feet). If the area is already known, it may be directly entered into Step 2.

Due to current limitations, this calculator is only able to make determinations based on a rectangular room. As such, only the length and width (or rectangular area) is needed to establish a floor plan. If your project is more complex, you can always break your area down into smaller rectangles that can be entered individually into the calculator by pressing the “Add Area” button.

Ceiling Height

Ceiling height should be measured in feet from above the finished floor to below the finished ceiling. If the ceiling height is not known, leave it blank and enter the air change rate.

Air Change Rate

Air change rate, measured in air changes per hour (ACPH or ACH), is calculated by dividing the hourly volumetric flow rate by the volume of the area to be covered. Usually, flow rate is measured in cubic feet per minute (CFM), so this value would need to be multiplied by 60 (minutes per hour) before dividing by the volume (length x width x height). If this value is not known or cannot be computed, leave it blank and ensure that ceiling height is entered.

Gas Type

Select your target gas to be measured from the following gases: Carbon Monoxide (CO), Nitrogen Dioxide (NO2), and Oxygen (O2). At least one gas must be selected.

Input Voltage

Select the voltage that you will be supplying the gas detector. Note that not all Brasch models support both input voltages. As such, you may want to consider running the calculation more than once with different input voltages to see if there is a product better suited for your application.


The number of sensors is how many individual sensors are required for your project. For GSE units, each detector is capable of supporting a maximum of 2 sensors. For GDCP-A units, each detector is capable of supporting a maximum of 20 sensors.

Your recommended detector(s) will be the simplest option based on the number of sensors required for the area to be covered. This is only a recommendation and not the only option that will work. For more advanced areas or specific use cases, other detector models are available in a variety of configurations. Click on the image to learn more about the recommended product(s).


For more assistance, please contact Brasch Environmental Technologies.
Phone: 314-291-0440