Experience Guide

Experience Gain
The party gains experience (as a whole) by successfully completing missions / assignments, killing enemies or finding new Codex info. The experience gained is based on the level of the party, the higher the level, the more experience will be awarded. The exact formula is:

Experience Gained = BASExMODIFIERxAWARD TYPE (rounded down) where BASE is a fixed value for this AWARD TYPE. For example, most codex entries on the citadel station (perhaps everywhere) have an exp. base of 2. This means, on level 5, the party should get 10 experience points for finding a new info (without bonuses). In the Citadel: Scan the Keepers assignment, every scanned keeper will give experience points, here the exp. base is also 2, meaning that on level 6, 12 points will be awarded.
 * BASE: From Levels 1-5 = 5                   From Levels 6 and higher = Level
 * MODIFIER: This number ranges from 2.0 to 2.4 Depending on which Experience Achievements have been Unlocked from 0% to 20% total
 * AWARD TYPE: The Action for which the Experience was gained ranging from codex Entries to Assignments to Thresher Maw kills

This means, that normally it does not matter, when missions / assignments are completed. It doesn't make sense to solve assignments later to get more experience points, because there will be less experience points for all other things until then - both effects will cancel each other out.

Maximizing Experience
As the number of enemies is limited, there is no way to fight endless hordes of enemies, so every experience point is valuable. There seem to be some ways of getting most experience out of the game, the first ones being rather ineffective:

By trying to reach the needed experience points for a certain level exactly, the points that are "wasted" can be minimized. Example: Let's say that the actual value is 1490 (level 5 - level 6 starts with 1500) and there are two possibilities - earning 100 (exp. base 20) now or earning 10 (exp. base 2) now. It's better to take the 10 points now:


 * 1) If the 100 points are taken now, experience will be 1590. Then the 10 points will become 12 points (because level is now 6), giving 1602 points at all.
 * 2) On the other hand, if the 10 points are taken now, experience will be 1500. The 100 points will become 120 points (because of level 6 instead of 5), making it 1620 points together.

Of course, this method is not very effective, because it will only affect one experience gain after each level, making the effect rather small.

Becoming a Spectre will usually give you enough experience points to reach the next level, particularly on new characters. It's recommended to become a Spectre as late as possible, directly after reaching a level, so the points gained can be maximized however it may make no difference on a high level repeat playthrough.

The last (and most effective) way is simple: Don't fight inside the Mako. Experience awards while in the Mako, regardless of whether the Mako damaged the target or not, are severely penalized at 50% on Normal level and 60% (granting only 40% xp gain) on Insanity. Using damage over time effect like Warp, Sabotage, Chemical Rounds, Inferno Rounds, etc, or pushing the target over a fatal drop, still incur a penalty if you are inside the Mako when the target dies. By leaving the Mako, it is possible to get much more experience points for fighting on planets. The important thing here seems to be the kill, so a good tactic (especially for bigger enemies) is to fight with the Mako's weapons until the enemy has only little health left - then leave the vehicle and kill it. This tactic works fine with Thresher Maws, for example.

There is a technique to gain more experience during the siege of the Citadel. When you first exit the elevator, or when you are walking on the exhaust plains just before the turrets, there is a corridor blocked by krogan and geth troops. Out of the far side a Geth Destroyer will come around the corner toward you; soon after you kill it another one will appear, then another. They stop coming when you reach the opposite corner. Another strategy is to leave one krogan alive and use AI Hacking on the Geth Destroyer as it comes around the corner. Unfortunately they will stop coming after a while (7 or 8 seems to be the limit). This "stream of spawns" also holds true in Bring Down the Sky for rocket drones launched from the top floor of the second torch station (the one with the mine field) on X57, as long as you leave at least 1-2 enemies alive on the ground floor.

Gaining Items
Finally, it's important to bear in mind that your experience level affects the level of items gained from containers. Levelling up is strongly recommended before opening containers as you'll gain better equipment. For example, if you're playing an Engineer or rely on tech-savvy squadmates, it's often a good idea to leave Bring Down the Sky until later in the game when you have a higher level, as it will allow you to get high-powered omni-tools that are very difficult to find elsewhere. This effect works both ways, however, so any rank VII items desired should be focused on and acquired before the player character advances beyond the maximum level where they are available, approximately level 37. Many ammo, weapon, and armor upgrades change effects between levels VII and VIII or in some cases disappear entirely.

Starting with level seven, every sixth level you gain more advanced items from containers and enemies than you previously got.

This table is meant as a reference and mostly applies to normal drops, such as containers. Hard decryption containers and special enemies may give you items one level higher than average, and merchants may sell equipment two levels higher, for instance.

Level progression
The following table illustrates the levelling scheme used in Mass Effect. The Incr column lists the incremental increase of required experience points. The experience points requirement are calculated based on the last level up – for example: levelling up from level 11 to level 12, requires 1,100xp. To level up from level 12 to level 13 will require 1,100xp + 100xp.