Larger than the 30L Travel Bag, the 40L Travel Bag is designed for longer excursions. Some might say a week, but we think you don't need much more for a month than you do for a week, so we'd definitely take this on a multi-month backpacking trip around Europe or South America (or wherever).

The primary difference between a 30L and 40L backpack is their utility and airline compatibility. A 30L backpack is widely considered the "sweet spot" for minimalist weekend travel or "personal item" use; it is typically compact enough to fit under most airplane seats and forces the traveler to pack efficiently. In contrast, a 40L backpack is the maximum size allowed for a standard "carry-on" in the overhead bin (usually 22 x 14 x 9 inches). A 40L pack offers significantly more room for a week's worth of clothes and a pair of extra shoes, but it is often too bulky to be comfortable for long-distance walking or public transit. In 2026, many 40L packs include hip belts and internal frames to distribute the weight, whereas 30L packs are often simpler and lighter. If you are a "one-bag" traveler looking to avoid all baggage fees on budget airlines, the 30L is your best bet, while the 40L is the "professional standard" for those who want to maximize their carry-on space for longer international journeys.