In the past I have been confronted with the difference between liters and kilos before causing problems in realizing the relation between the two. The confusion was created by a bag of sand that contained much more liters than kilos. Now I found a suitcase which advertises a content of 20 liters. It is a really huge suitcase. I regularly buy bottled water in an 8 liter container and I am sure 4 of these bottles could easily fit inside the suitcase. 4 bottles of 8 liters water is still 32 liters of water and this is much more than should oficially fit inside the suitcase.

Probably the manufacturer of the suitcase specifies the 20 liter limit because many airports have a weight limit per suitcase of 20 kilos. 1 kilo is equal to 1 liter, so it is easy to figure out the limit to place on the bag. It is easy, but incorrect. The suitcase is being sold with a content of 20 liters, but it easily fits 32 liters. Why sell something for less that it is? And why is the content of the suitcase expressed in weight? Is it not easier to design a new system where you indicate more clearly how many items fit inside the bag.