Experience



Experience can be obtained by gathering Experience Orbs from defeated mobs and players. Experience is used for Enchanting. The experience system has been changed in Snapshot 12w22a.

Behavior
Gathering experience points increases the player's experience level by gradually filling a bar on the bottom of the screen until a new level is achieved when the bar is full. When the player dies, they drop 7 times their level as experience orbs, up to a maximum of 100 points (enough to reach level 6). All the other experience vanishes.

Each level does not get harder to earn than the last.

Experience Orbs will not drop from a mob unless the mob is killed by a player or damaged by the player and then killed by other means; therefore ordinary mob grinders cannot be used for farming experience (although grinders can be designed to funnel monsters to a holding location, and wear them down to one-hit kills). Experience orbs will "float" or glide toward the player if they are 2-3 blocks away.

Mobs will drop a random number of orbs, and the orbs can have different values. However, the total value will always remain within these values, regardless of difficulty setting:



Leveling Up
Note: In 12w22a and later, levels DO NOT get harder to achieve as they get higher! This means that getting from 1-10 needs the same amount of exp as 11-20. The graph below is only relevant in versions before this snapshot.  XP required,XP diff 0,0 7,7 17,10 31,14 48,17 69,21 93,24 121,28 152,31 187,35 225,38 267,42 312,45 361,49 413,52 469,56 528,59 591,63 657,66 727,70 800,73 877,77 957,80 1041,84 1128,87 1219,91 1313,94 1411,98 1512,101 1617,105 1725,108 1837,112 1952,115 2071,119 2193,122 2319,126 2448,129 2581,133 2717,136 2857,140 3000,143 3147,147 3297,150 3451,154 3608,157 3769,161 3933,164 4101,168 4447,175 4625,178  

History

 * A precursor to the experience system was the point system in Classic Survival Test
 * Experience was originally revealed by Jeb during an interview. Jeb released a picture of the 1.8 GUI list, which shows the experience bar, among other things.
 * Experience was added in Beta 1.8 but there was no measurable benefit to gaining Experience Orbs and levels.
 * Experience orbs once despawned if a player slept before collecting them. This meant that if you died at night and slept before collecting your items, the orbs would disappear when you woke up. This has been fixed; if you sleep after you die, your experience will still be there.
 * The ability to spend experience levels for Enchanting items was added in 1.0. Experience requirements were also changed in this update.
 * As of weekly snapshot 12w04a the Bottle o' Enchanting was added but is only useful for adventure maps since you don't need any experience when enchanting in creative mode in the snapshot 12w05a.
 * As of snapshot 12w22a, players can get XP from mining, breaking mob spawners, and smelting in a furnace. A very large amount of experience can be collected while mining, sometimes into the hundreds of levels. Coal, lapis lazuli, redstone, diamond and emerald ore give you experience points. However, iron and gold ore don't give experience when mined to avoid easily getting xp from mining and placing the block constantly. However, smelting the ore blocks gives the experience.
 * As of snapshot 12w22a, XP levels now increases with a fixed number of 17 XP Orbs instead of exponantially (before 12w22a), so killing the Enderdragon will now give approximatly 1176 XP Levels (instead of ~ 105 before 12w22a). Levels do not get harder to achieve as they get higher. This means that getting from 1-10 needs the same amount of exp as 11-20.
 * Before 12w22a, to reach level 50, which is the number of skill points required to purchase the highest type of enchantment, one would need to gather 4625 experience by defeating 925 hostile mobs. This isn't the case in snapshot 12w22a which requires considerably less to get into higher levels (The amount which would usually get the player to level 30 now gets them to level 93), this is because the leveling system no longer makes each level harder to get from the last. Getting from level 1 to 10 needs the same experience as 11 to 20. The following graphs are relevant for versions before this snapshot:

 XP required,XP diff 0,0 7,7 17,10 31,14 48,17 69,21 93,24 121,28 152,31 187,35 225,38 267,42 312,45 361,49 413,52 469,56 528,59 591,63 657,66 727,70 800,73 877,77 957,80 1041,84 1128,87 1219,91 1313,94 1411,98 1512,101 1617,105 1725,108 1837,112 1952,115 2071,119 2193,122 2319,126 2448,129 2581,133 2717,136 2857,140 3000,143 3147,147 3297,150 3451,154 3608,157 3769,161 3933,164 4101,168 4447,175 4625,178  

Trivia

 * When enchanting, the experience levels used will be subtracted from your current level, not your current XP total. This has important implications for leveling above 50--the levels gained will have a high XP cost, but this will not be preserved. For example, if you are enchanting anything at level 50: if you earn enough experience to get to level 51, then enchant, you will be left at level 1. If you had enchanted first, and collected the same amount of experience afterward, you would have reached level 8.
 * Experience orbs will drop from a mob if it dies within 5 seconds of being hit by a player. This means you can use fall damage by knocking mobs off a cliff.
 * Using enchantments does not decrease your score (which is shown on death).
 * In the resources folder of Minecraft, there appears to be an unused sound of leveling up. It cannot be heard in gameplay.
 * If you gain too many experience points (such as a trillion through server commands), the experience bar will disappear altogether as well as your level on your HUD. This appears to occur around level 32,767 (the largest value representable as a 16-bit signed integer).
 * Dying in the Nether causes enough dropped experience orbs to disappear, that you will have dropped 30 experience levels.
 * One can determine how much experience has been collected to reach a level using the equation:
 * Total Experience = 1.75[Level]2 + 5.00[Level]
 * This equation does not include any experience that is currently filling the experience bar.
 * Additionally, the amount of experience required to advance to the next level can be calculated using the equation:
 * Experience Required = 3.5[Current Level] + 6.75
 * (NOTE: When performing these calculations, answers should be rounded to the nearest integer, using the "Round half away from zero" rules.)


 * From one large slime, the minimum experience you can get from killing it and all the slimes that split from it is 12, 4 from the largest, 2 from the 2 it splits into, and 1 from the 2 each of those split into. The maximum experience possible is if the big slime splits into 4 and each of those medium slimes split into 4, resulting is 28 total experience.

Bugs

 * Experience is not always rewarded after killing an animal/mob/player, this may be due to effects such as "Fire Aspect" for swords which do additional damage and that damage may not be attributed to you. Animals/mobs should give experience 100% of the time if you use a standard sword and the killing blow is yours.
 * When bringing a single player map into a server, the experience for one's single player will be reset.

Upcoming features
Each level up will potentially reward the player with Skill Points, which Notch has said may be used for buying things such as increased jump height and increased maximum health.