XP (probably derived from the word experience) is a type of currency in Battle Cats. XP is gained from completing stages and spent on upgrading cats and special skills. No XP is awarded if the player escapes or is defeated.
The amount of XP gained from the end of each battle follows a formula which is dependent on several factors:
The base XP is a number assigned to each stage. The stages in story mode follow a simple formula: the base experience increases by 200 each stage. Korea, the first stage, begins at 1000 XP. Event stages have varying base XP.
The number of times 'cleared' for each stage is shown in the world map. As the Base Menu Cat says, "If you keep fighting in the same stages, you'll get less XP every time!" Each time a stage is replayed, the XP awarded is reduced by 1/14. From the 15th battle, this reduction stops such that 1/14 of the initial base XP is awarded. Other modifiers still apply.
Study is a Special Skill which may be upgraded up to level 10. Each upgrade increases the XP by 5%, which stacks additively. As Study can be upgraded 9 times, the maximum multiplier is 145%. It is recommended to max this skill out before Chapter 1 is completed.
Treasure bonuses such as from the philosopher stone can increase the amount of XP when a stage is cleared. These are activated when every treasure from a collection is acquired. The bonus from each collection is shown as 100% when all the treasures are of 'Superior' quality. This indicates that the bonus is maxed, however, it does not necessarily translate to a 100% increase in the XP award. See Treasure effects for explanation.
Due to rounding errors, the exact XP awarded might differ slightly from the formula shown below.
Or more precisely,
For example, if the player is clearing Saudi Arabia for the 4th time, and has a Study upgrade level of 10 but no treasure bonuses, the expected XP is 4900*(11/14)*1.45*1, which is about 5583.