Levels and XP

The very first level of a run costs a flat 150 XP, the amount the run starts with on its bar. Every level after that costs 150 multiplied by 1.25 raised to the level you have just reached, plus 200, rounded down. Levelling several times at once raises that power by one for each level you are behind, so banking levels never makes them cheaper.

XP picked up is multiplied by XP Gain before it is added.

While a level up is waiting to be taken, your XP gain gets a bonus of 5% for each level waiting, up to 5 levels, so at most 25%. The bonus counts the levels you have banked and is set again each time one is added.

Once you take the level up cards, the bonus goes back to 0. Banking levels therefore makes the next ones come faster, but each one still costs what the curve above says.