Calculate how many place settings a dishwasher can wash per load.
Dishwasher capacity is quoted in place settings, and a place setting is a defined set under EN 50242 — a dinner plate, soup bowl, dessert plate, cup, saucer, glass and the cutlery that goes with them. A 24 in full-size tub is rated at 12 to 14 settings and an 18 in slimline at 8 to 10, with a third rack adding roughly two settings' worth by taking the cutlery out of the baskets. On the demand side, not every meal generates a full setting — snacks and breakfasts are lighter — so the daily figure is discounted to about three quarters of a setting per meal per person. The resulting loads-per-day is the number that tells you whether you can run one cycle after dinner or need two.
Dishwasher Capacity
Settings per load = 12 (24 in) or 8 (18 in), plus 2 for a third rack; daily settings = people x meals x 0.75; loads per day = daily settings / settings per load
It works out at roughly one and a half loads a day rather than one, so you will run it twice on cooking-heavy days. For four people a full-size tub is usually the better buy.
No, it changes duration and water temperature. The rated place settings are the same; eco just takes two to four hours to get there using less energy.
Wait. Modern dishwashers use 3-4 gallons per cycle regardless of how full they are, so the cost per item drops sharply the fuller the load — half-load buttons save less than they suggest.