On many ships, basic inside and outside cabins are usually the same size, the difference being that one has a porthole or picture window to let in natural light. Balcony cabins can also be the same size as standard insides and outsides, with the addition of the outdoor space on the verandah; sometimes the interior space is larger. A basic cabin, regardless of category, is referred to as a "standard" unless there is something about it that makes it different (such as physical layout, being handicapped accessible or a designated family cabin). With minisuites on up, you get bigger and bigger indoor and outdoor spaces.
For many travelers, the decision on what size cabin to get is directly related to price. Who would not go for the huge suite if price were no obstacle? Yet it can be tricky to decide whether a balcony is worth the upgrade from a standard outside, or which suite to choose. Here are a few size-related considerations to take into account.
Exception: Carnival has several cabins which are classified as inside cabins but actually have a french glass door which allows light into the room (no balcony, but the door can be opened). Carnival also has some cabins that have a window, but because the window has an obstructed view (that means there is a railing or object in the way) it is listed as an inside cabin. Royal Caribbean has some cabins that have a window but look out over an inside promenade area. These are called "promenade staterooms".
Some cruise travelers prefer their cabins to be near to (or far away from) specific areas of the ship. Sun-worshippers might prefer an upper-deck location close to the pools and sun decks, while partiers might want easy access to midship entertainment hubs. Travelers with mobility concerns may prefer a stateroom close to a bank of elevators.