Level

Levels are the general competency of the player character in the SPECIAL character system. A measure of experience and abilities. The level is determined by the amount of Experience Points the player character has earned throughout their journey.

Level up
Fallout, Fallout 2 and Fallout Tactics Level Up

Fallout 3 Level Up

Fallout New Vegas Level Up Each time one levels up, they have the option to modify skills but not primary statistics. They can also gain special perks. Therefore, the player character becomes stronger and better with each level gained.

Level cap
The maximum level reachable varies from game to game:
 * Fallout: 21
 * Fallout 2, Fallout Tactics, and Fallout: Brotherhood of Steel: 99
 * Fallout 3: 20 (30 with the Broken Steel add-on)
 * Fallout: New Vegas: 30–50; each of the four add-ons raises the level cap by 5 levels
 * Fallout 4 does not have a level cap; however, the game crashes once reaching level 65,535.

Bugs

 * There may be a glitch that will not let you keep your perks after level 30.
 * Levels 20-29 will all register as Last, Best Hope of Humanity for a good Karma player character in the Pip-Boy Stats screen.

Fallout: New Vegas
* Your character must also not have the Logan's Loophole trait, as this caps your level at 30.

Fallout 4

 * When the Sole Survivor levels up, they can choose to either increase one of the seven S.P.E.C.I.A.L. stats or rank up one of the seventy perks available.
 * Fallout 4 doesn't have an actual level cap, but the hard limit is 65,535 (Hex number FFFF) . Trying to level past this point by any means will crash the game due to the value overflowing back to zero.
 * Reaching level 278 will allow the player character to acquire all perks and 10 S.P.E.C.I.A.L. (11 if bobbleheads are taken with 10 of a stat). This level is 285 if only Far Harbor, or Nuka-World is installed, and 292 with both.

The number of points to earn in level n in order to progress to the next are:
 * $$\Delta\mathrm{XP}_n=75\cdot(n-1)+200\,.$$

Simplified:
 * $$\Delta\mathrm{XP}_n=75n+125\,.$$

The XP thresholds for level n are thus:
 * $$XP_n=37.5\cdot n^2+87.5\cdot n-124\,.$$