A 1.5-liter lunch box fits most adult lunches.

A 1.5-liter lunch box fits most adult lunches, and 2 liters is the right call if you meal prep or have a serious appetite.

Do the math on what you actually pack. A typical lunch is a main dish around 500–700ml, a side or snack around 250–400ml, and something for dessert. That lands right at 1.2–1.5 liters. If you’re just doing a sandwich, chips, and an apple, even a 1-liter box works fine.

Beware of the marketing. Brands list total volume, including the space taken up by dividers, so a “1.5L” bento box often holds noticeably less than a plain container of the same rating. And if you’re reheating anything, leave a little headroom.

When in doubt, round up. A slightly baggy box is no big deal; a lid you have to wrestle shut gets old by Wednesday.