Does multiclassing have an effect on exp/levelling up?

Question

My understanding of the multiclassing system is a little vague, so I wanted to clarify. If I was to use multiclassing to level up, and increase my overall level, how does the exp get dispersed between the classes? For example, If I was say, a level 3 fighter, then I took on another class, this would bring my overall level to 4.

Does each class work individually in terms of exp? I.e. I might need 3000 exp to level up from level 3, but only 1000 exp to level up from level 1.

Or does it work in an overall sense? A level 3 Character (multiclass or not) requires 3000 exp to level up to level 4, and can then choose what to spend the level up on?

Answer 1

It's all the same.

The experience point cost to gain a level is always based on your total character level, as shown in the Character Advancement table in chapter 1, not your level in a particular class. (PHB, p. 163, "Multiclassing: Experience Points")

The amount of XP you need to go from Fighter 3 to Fighter 4 is the same amount of XP you need to go from Fighter 3 to Fighter 3/Druid 1: 1800 xp.

See the "Character Advancement" table (as referenced in the quote above) on page 15 of the Player's Handbook. And when you read it, note that the XP numbers listed are total XP, not how much more you need on top of your existing XP to get to that level. So 3rd level to 4th is 2700 − 900 = 1800 more XP, not 2700 more XP.