Determining the quantity of soffit vents required for your attic depends on factors such as attic size, roof pitch, and ventilation efficiency. Generally, for every 100 square feet of attic space, you’ll need at least one square foot of ventilation. If your attic has a high-efficiency ventilation system, such as a ridge vent, you may need less soffit venting. Conversely, if your attic has a low-efficiency ventilation system, such as a gable vent, you may need more soffit venting. Consult with a roofing professional to determine the optimal number of soffit vents for your specific attic.