Experience point

An experience point (abbreviated XP or EXP) is a unit of measurement for character level advancement. Advancing to the next level requires a fixed amount of experience points which is determined by a formula.

Gaining levels is based on the concept that as characters defeat stronger enemies, they gain combat experience that allows them to improve their skills. This system was established in the 1970s by the classic pen-and-paper RPG Dungeons & Dragons and is present in some form or another in almost all role-playing games.

In World of Warcraft, you generally get XP from killing mobs and completing quests, but you can also get some from exploring, gathering herbs, mining, collecting fragments with Archaeology and opening chests. Since patch 3.2.0, XP is awarded also for completing objectives and actions that yield honor in Battlegrounds (honorable kills not included).

Another notable source of XP is completing instance runs with a random group matched together via the Dungeon Finder (unlocked at level 15). In addition to the normal rewards in an instance, players are rewarded extra XP and gold on completion of the run.

In summation, there are three alternative activities that can be utilized while leveling your character -- questing, dungeons and battlegrounds. When a player grows tired of one mode of gameplay they can switch to another.

Rest bonus
While in an inn or anywhere in a capital city, your player portrait will begin to glow and your level circle will say zzz, indicating that you are resting. If you log off here, you will continue to rest while offline.

When rested, your XP bar will turn blue, and a notch will appear indicating exactly how rested you are. (If there isn't enough room to show it on your current XP bar, it will show up after you gain a level.) You will earn double XP from killing monsters, mining ore nodes, gathering herbs, collecting archaeology fragments, and opening chests while rested until your XP bar fills to the notch. At that point, the message
 * You feel normal.

will appear and you will resume normal XP gains.

One bubble of rested XP (5% of your current level) is earned for every 8 hours spent resting. A maximum of 30 bubbles (150% of your current level) may be earned. In other words, you can leave your character resting in an inn or capital city for up to 10 days (without gaining experience) before you earn the maximum amount of rest state, and a resting character stores up one full level of rest in 160 hours (6.67 days).

Other XP bonuses
Many heirloom items grant greater XP gains while wearing them. The XP bonuses stack with each other and with the rest bonus. The effect of some heirlooms stops at level 80, while some remain active all the way to 85.
 * Brewfest Enthusiast (+10% to all experience gains, 2 hours). Awarded by being present for the tapping of the keg on the Brewfest grounds at 6:15 (AM and PM) each day during Brewfest.
 * Essence of Wintergrasp (+5% experience from monster kills in Northrend and Northrend dungeons), a buff granted when the player's faction holds Wintergrasp.
 * Learning by Example (+10% quest experience) a one hour buff sometimes granted by Adventurer's Journal.
 * Enlightenment (spell) (+50% from monster kills and quests, 1 hour) is a one hour buff available to Monks from class-specific quests (given in the Shrine of the Ox accessed by the Monk skill Zen Pilgrimage).
 * Unburdened (+10% experience and reputation), a one hour buff granted by clicking the Wickerman bonfire during Hallow's End.
 * Enlisted (+10% experience), a buff for toggling War Mode on. A Call to Arms could increase the bonus to +20%.

XP in a group
A multiplied amount of XP is divided between party members in the same area when a mob is defeated by a member, the factor increasing with each additional player in the party. Two-member parties have a slightly different formula. The division of XP among party members is a calculation based on the various levels of the party members and the level of the mob.

The net result for a player in a group is less XP per monster. Experience from other sources (quests, etc.) is not affected.

XP from monsters in a raid group is dramatically decreased.

Disabling XP gain
If you do not want to gain XP, you can visit Behsten (Alliance) or Slahtz (Horde) to turn off all experience gain. It costs to disable XP gain, and another  to re-enable it. Be aware that any potential XP gains wasted in this way cannot be recovered. Disabling XP gain does not affect the gain of guild experience or guild reputation from turning in quests. Disabling experience applys the Experience Eliminated buff.

This is useful for players who wish to stay in a battleground bracket (say 15-19) while still able to farm for better equipment and kill monsters without reaching level 20. This is called twinking. Players with XP gain disabled (twinks) are matched against other twinks in the battleground queue system.

Another use for this feature is visiting old content at the original level, e.g. Burning Crusade raids at level 70. Herald of the Titans is an achievement that requires all members of the raid to be level 80.

Out-leveling zones
If you are at or above the maximum level for a given expansion, killing creatures from that expansion's zones will only give 10% of normal experience. Quests will continue to give their standard EXP, or gold for level-capped players.

Example:
 * If you are at level 60 or higher and you choose to stay in the old world and not move on to Outland, killing creatures in old world zones will only award 10% of normal experience.
 * If you are at level 70 or higher and choose to stay in Outland and not move on to Northrend, killing creatures in Outland will only award 10% of normal experience.
 * If you are at level 80 or higher and choose to stay in Northrend and not move onto Cataclysm zones, killing creatures in Northrend will only award 10% of normal experience.

Mob gray level
Killing a mob stops giving XP if the level of that mob is too low. The mob name will have turned gray. The mob level at which this happens is called the Gray Level, and depends on your character level.

The full formula for the Gray Level is rather complicated, so here is a table. Mobs at or below the level given in the table do not give XP.


 * A Gray Level of 0 means that no mobs are gray at that character level.
 * The lower the Gray Level (bigger difference between character level and the gray level) the better for the player, as it means more mobs to give XP.
 * For character level 6-39 there is a little jump in favor of the player every 10 levels.
 * For character level 40-59 there is a little jump in favor of the player every 5 levels.
 * At character level 60 there is a big jump to the disadvantage of the player.
 * For character level 60-85 the Gray Level is simply 9 levels below the character.

Quest XP
The following formula for quest XP was obtained by studying the XP rewards provided for various quests and various levels. Character_Level <= Quest_Level + 5 : Quest_XP = (100 %) or Full_Quest_XP Character_Level = Quest_Level +  6 : Quest_XP = ( 80 %) or ROUND(Full_Quest_XP * 0.8 / 5) * 5 Character_Level = Quest_Level +  7 : Quest_XP = ( 60 %) or ROUND(Full_Quest_XP * 0.6 / 5) * 5 Character_Level = Quest_Level +  8 : Quest_XP = ( 40 %) or ROUND(Full_Quest_XP * 0.4 / 5) * 5 Character_Level = Quest_Level +  9 : Quest_XP = ( 20 %) or ROUND(Full_Quest_XP * 0.2 / 5) * 5 Character_Level >= Quest_Level + 10 : Quest_XP = ( 10 %) or ROUND(Full_Quest_XP * 0.1 / 5) * 5 Some lower level quests (Quest_Level < 10) seem to give full XP only for Character_Level <= Quest_Level + 4, differing by 1 level with the table above.

For the table, see Mob difficulty colors.

Blizzard has awarded full xp for the completion of a quest of any color except grey. See Wow-Europe. The level at which a quest becomes green is exactly the same as for mobs.

In respect to current level, higher level quests do yield a larger relative xp gain. However, in the time it takes to do these harder quests it is possible to do several of the lower quests. Each to their own, but don't confuse the absolute value of xp gained as a number with the relative xp gained as a percentage of current level requirements. One strategy is to avoid reds, miss most oranges and focus on a mix of yellow and greens. If you are meant to do them then you will find you have time later. If by then you have already moved on, there are plenty of shiny new quests in the next zone.

Also, bear in mind that by completing higher as opposed to lower level quests, you may reach a point where the quests below you are grey and you're not high enough level to pick up any new ones, and will have to move to a new area to get quests.

Match the green and yellow quests and there is more than enough to see you questing all the way through the game.

Money for experience at top level
When a character has reached the highest level attainable, depending on the current expansion, they will receive money instead of experience points. In this case the normal gold reward a quest may give is not awarded. However, the xp to gold conversion always results in a larger gold reward than the normal gold reward. As far as can be determined, the conversion formula is: Money in copper = XP * 6 (Level 1-80 quests) Money in copper = XP * 2.383285303 (Cataclysm 81-85 quests) For example, a player with the expansions up to Wrath of the Lich King completes a quest at level 80 that normally awards 7 gold and 22,050 experience points. The player would instead receive from the xp to gold conversion, but they would not receive the normal 7 gold reward in addition to that. Players who have turned off their experience gains by visiting Behsten or Slahtz do not get any money in compensation for the XP they would otherwise gain.

Note that some sources of XP, such as battlegrounds, do not reward players max level players with gold in place of XP.

Experience to level
The experience needed for a given level is specified by a formula that takes in to account several different factors. Up to level 10, it takes 8*CL kills of creatures of your same level to advance to the next level, where CL is your Current Level.

At level 11, the "difficulty reduction factor" added in patch 2.3.0 will kick in, thus reducing the XP needed to level. Though this initially lasted until level 30, the reduction factor was extended to level 60 with the release of Cataclysm. The general purpose of these difficulty reduction factors is to keep the total time spent leveling a character relatively constant, despite the level cap increasing with each expansion.

At level 60, the expected XP from killing a mob of your level increases significantly, as it is assumed that you will be killing mobs in Outland. This increases XP required to level. At the same time, however, another reduction factor (active 60-70 only, added at the release of WotLK and adjusted for Cataclysm) goes into effect reducing the XP needed.

At level 70, the expected XP from killing a mob of your level increases drastically again, as it is assumed that you will be killing mobs in Northrend. The 60-70 XP reduction factor changes to a different factor added at the release of Cataclysm; however, this is less of a reduction, so players will see a large jump in the XP needed to level compared to what they had in Outland. A further reduction of EXP needed at levels 60-80 is planned for Patch 4.3.

The total experience needed to reach level 60 is 3,379,400.

The total experience needed to level from 60 to 70 is 4,722,000.

The total experience needed to level from 70 to 80 is 15,965,800.

The total experience needed to level from 80 to 85 is 22,180,300.

The grand total experience needed to level from 1 to 85 is 46,247,500.

Trivia

 * During the game's beta, players would lose experience when they died.