Upon reaching rank 42, players will begin earning a lower percentage of the XP they would otherwise earn, with this penalty increasing per-rank, capping out at max-rank players at level 50 only receiving 50% of the XP they earn for a win. In order to maintain this system, the higher-ranked players begin seeing the opposite affect applied to their wins. However, Halo 2's online XP is a zero-sum system, meaning that there is a set amount of XP points available to the entire player population as a whole, and the raw XP gain/loss systems ensure when a player loses against another player, the winning player gains the same amount of XP as lost by the loser. This % value peters off as they level up and by rank 29, is no longer in effect. In order to help new players in being able to level up, lower-ranked players are not penalised as hard when losing matches while they are low-leveled. With the systems listed above, one last consideration is the XP modifiers given by rank. The matchup requirements are listed below. The 1-50 rank held by a given player determines which players they will match up with in multiplayer matchmaking, by aiming to match players up with similarly-ranked players. For example, if a player needs 10,000XP to hit a new rank, achieves 10,000XP but then loses a game and drops below the 10,000XP total, they won't revert back to the previous level until their XP total hits 5,000XP. However, in order to prevent frustration at constantly flipping between two ranks if games are repeatedly won and lost, players will keep their 1-50 rank value even if they drop below the original requirements to achieve it, and won't de-rank until they hit the mid-point of the previous rank's requirement. Each rank has an XP bracket assigned (shown below). Each rank has a simple icon alongside its number, with the final seven ranks holding a unique symbol - a nod to Bungie's love for the number. Ranks are indicated by a 1-50 value, with a new player holding rank 1 and the highest-ranked players holding rank 50, with most players averaging around rank 10. With the player's total XP values known, the game can display a single rank number as a representative of their overall skill. This calculation is done for every player to determine each player's XP gain/loss. This value is then summed to get a total of 234, before divided by three to get an average value of +74XP. Thus, it can be determined that Player A earned 79, 85 and 70 XP - respectively. In this case, they won against a player with a three level difference, a two level difference and a five level difference.

To calculate Player A's total XP gain, the table must be consulted three times - once for each player they matched up again. To give an example of this system in use, consider a free-for-all match in which there are four players Once these values are tallied, the total is divided by the amount of enemy players, to gain a final XP value for the game as a whole. For a given player in the game, the table is consulted to perform a matchup against every single player of an enemy team in the game - if the player has completed a match of 8v8 slayer, the table would be consulted to determine the XP gain/loss for all eight opposing players. In broad terms, winning or losing matches against similarly-ranked players nets a lower XP gain/loss, whereas winning matches against players with higher skill gaps will gain greater rewards or greater loss. This is achieved by consulting a table (shown below), dependant on the difference in level. Once a game is completed, the game awards or removes XP from each player depending on the final result. Rank is calculated per-playlist, meaning that a player's performance in one playlist does not affect their rank in another.

Ranks are calculated purely on wins and losses, meaning actual in-game performance such as KDR, Flag captures, bomb plants, hills captured etc do not affect the final result merely being on the team does. Each game completed awards or removes XP, depending on the result of the match - this means that poor performance in a game can result in losing rank, while winning results in players ranking up. The displayed 1-50 rank is an abstraction of an XP value, hidden to the player and calculated behind-the-scenes. When matching players for online games, the algorithms in question try and pair up similarly-skilled players to ensure roughly evenly-matched games. Halo 2 uses a skill-based matchmaking system, informed by a numeric value of 1-50 to represent a given player's skill level in any given playlist.

Halo ranks ranks