Commercial Dishwasher Calculator

The right dishwasher size comes down to how many racks of dishes need washing during your single busiest hour, not your daily average — a machine that can keep up on a slow Tuesday afternoon can still fall behind during Friday dinner rush. This calculator first estimates total daily covers as seats times turns-per-meal-period times number of meal periods, then converts covers to racks using a standard planning ratio of about 0.33 racks per cover (roughly 3 covers per rack) inflated by 20% to account for pots, pans, utensils, and glassware beyond the plates themselves. Peak-hour demand is derived by applying your peak-hour percentage — the share of the day's covers concentrated into the busiest single hour, typically 30-50% — to that daily total, then converting to racks the same way. That peak racks-per-hour figure is what actually selects the machine type, walking up a tiered scale from under-counter (up to 30 racks/hr) through single and double door-type machines, single-tank and multi-tank conveyors, and finally flight-type for institutional volumes above 350 racks/hr.

Water and energy use scale with total daily racks, but the per-rack rate improves as machine type gets larger and more efficient — conveyors use less water and power per rack than a small door-type unit. Labor hours are estimated assuming one dishwasher can process about 35 racks per hour with a typical door-type machine, so this labor figure may run high for kitchens with faster conveyor equipment. Keep in mind the calculator picks a machine based on your peak hour alone — if that peak estimate is too low, the recommended machine may bottleneck during your actual rush.