Precise jump in units

Hi, I’m trying to find out how I can make precise jumps with a character.

I’ve found character’s JumpZVelocity is default 420, Project settings: Gravity Z is default -980.

Through testing I found the max height for the character to be able to jump upon a box (or whatever) is 120 units.

I have no idea how these 3 numbers have in common because I sure can’t figure it out.

How can I make the character make a precise height jump (in blueprint or via their CharacterMovement component)?