23 kg is a weight limit, not a size: it's the usual maximum for checked luggage on most traditional airlines. There's no fixed size tied to that weight. A quality medium suitcase (65-69 cm) usually weighs between 2.8 and 3.5 kg empty, leaving around 19-20 kg of real usable capacity for your clothes and belongings. A large suitcase (75-82 cm) has more room, but it's also easier to go over 23 kg if you pack it completely full. The practical tip: weigh your suitcase at home before you leave. The... Read more...

40 x 30 x 20 cm is the size of the personal item (small bag), not a cabin case. Airlines like Ryanair, Vueling and EasyJet let you carry one item... Read more...