Use the calculator below to estimate the required cubic feet per minute (CFM) needed to satisfy various air changes per hour (ACH) for a space. You can also modify the values to calculate the desired CFM from a set ACH setting. This calculator even lets you select from various space types to bring up recommended ACH values. This, along with the duct-sizing reference at the bottom, should allow you to properly size a ventilation system for anything from a small bathroom space to a large workshop.
Disclaimer: Pro Tool Reviews is providing these calculators “as-is” and is not responsible for over- or under-estimating or incorrect costs, calculations, or values. Please verify your estimates on your own or through your service or material provider before starting any job.