Typically, more of your net profit will come from the washers than from your dryers. When designing your store, you want as many washers as is feasible. Determining the proper number of dryers is a mathematic ratio of washer capacity. Remember that 65-75 percent of your total revenue may happen from Friday through Sunday. The most common "in hindsight" comment we hear from new store owners is that they did not put in enough dryer capacity and so had bottlenecks during peak periods which drove away customers. It's much easier to add in more dryers before the store is built than after the store is opened. As a side note, some commercial dryers will dry an average load faster than others. For best throughput, you want a fast cycle washer and dryer during your peak traffic periods.