I recommend a backpack around 40L-50L. Personally, I wouldn't go over 65L, but some people like a bigger bag. You can always go smaller, but I wouldn't recommend anything smaller than 35L — unless you're into minimalist travel.

For a two-week trip to Europe, the "high-fidelity" standard for most experienced travelers is a 40 to 45-liter carry-on backpack or a 21 to 22-inch (55cm) rolling suitcase. This size is ideal because it complies with most major airline overhead bin restrictions, saving you from checked bag fees and the risk of lost luggage during train transfers. If you plan on doing laundry halfway through your trip, a 40L bag is more than sufficient. However, if you are traveling in winter and need heavy coats, or if you plan on doing significant shopping, you might opt for a 60 to 75-liter checked suitcase. Keep in mind that European streets often feature cobblestones and many boutique hotels lack elevators, so a bag that is too heavy can be a major physical burden. Using packing cubes can help you maximize space in a smaller bag, allowing you to fit roughly 7 outfits, 2 pairs of shoes, and your toiletries. For 2026, the trend remains "less is more," as mobility is the key to enjoying Europe's dense urban centers and efficient rail networks.