A 20-liter (20L) backpack is generally considered a "small-to-medium" bag and its adequacy depends on the student's grade level and daily requirements. For a middle school or high school student who only carries a laptop/tablet, a couple of thin notebooks, a pencil case, and a lunchbox, 20L is usually "just enough." However, it often feels cramped if you need to carry a bulky physical textbook, a gym uniform, or a large winter jacket. For university students, 20L is often the "sweet spot" because many students have transitioned to digital notes and only need to carry a 13-inch laptop and a few personal items. If the bag has good internal organization (pockets for chargers, water bottles, and pens), it can feel larger than it is. In 2026, the "minimalist" trend favors 20L bags for their sleek look and ergonomic benefits—preventing over-packing and back strain—but if you are someone who "carries their whole life" to school, you might find a 25L or 30L bag more practical to avoid constantly cramming items in.