An 80 CFM fan and a 110 CFM fan can both be good choices. The better option depends on bathroom size, moisture level, ducting, and noise preference.
An 80 CFM fan often fits standard full bathrooms around 70 to 90 square feet with normal shower use. It may also be easier to use in some replacement projects because the ducting and ceiling opening may be closer to older fan sizes.
A 110 CFM fan is often better for bathrooms close to 100 square feet, no-window bathrooms, steamy showers, or rooms where the mirror stays foggy for a long time after use. The extra airflow can help, but only when the duct system can support it.
Do not choose only by CFM. Compare sones too. A quiet 110 CFM fan can be more comfortable than a noisy 80 CFM fan. If the bathroom is near a bedroom, look for a lower-sone model.
Bottom line: choose 80 CFM for smaller normal-use bathrooms and consider 110 CFM for larger or moisture-heavy bathrooms, after checking duct compatibility.
Calculate your bathroom fan size
Enter your bathroom dimensions and moisture situation to get a quick CFM estimate.
Use the CFM Calculator