A 20kg suitcase typically falls into the "Medium" (24-26 inches) category of luggage. While weight and volume are not perfectly correlated due to packing density, a medium-sized case (roughly 65cm×45cm×25cm) usually holds about 60 to 75 liters, which perfectly fits a 20kg limit for most travelers. If you use a "Large" (28-30 inch) suitcase, it is very easy to accidentally exceed 20kg because the extra volume invites overpacking. For a one-to-two-week trip, a medium case is the most efficient choice; it provides enough space for clothes, shoes, and toiletries without becoming so heavy that it is difficult to maneuver. Keep in mind that the weight of the empty suitcase itself (usually 3kg to 5kg) counts toward your 20kg limit, so choosing a lightweight hardshell or soft-sided case is a smart strategy to maximize your actual packing capacity.