If you're playing the Legendary Edition, this is locked at 100%.

The Readiness Rating is at 50% by default, but in the original release it can be increased by playing the multiplayer, the Mass Effect Infiltrator iOS game, and either Mass Effect 3 Datapad or the N7 HQ website.

The EMS required for a specific ending will be different if you're playing the original release, the original release with the Extended Cut DLC, or the Legendary Edition. It's the total strength of Shepard's War Assets with a penalty based on the Galactic Readiness Rating. This is the strength of Shepard's forces built up over the course of the game. Depending on their fate, certain EMS requirements for specific outcomes will be more difficult.

The fate of a character in an earlier section of the game.

If you started Mass Effect 3 fresh without using the Genesis 2 DLC comic, this will have been chosen for you.

The big choice you made at the end of Mass Effect 2.

Your options and their variations are influenced by three factors: There are eight different endings for Mass Effect 3: three core choices (two of which have two variations and the other having three) and one alternative ending available only in the Extended Cut. How Mass Effect 3's Endings Work (Spoiler-Free) While their requirements are revealed, their effects will be hidden.

The various ending permutations are described below.

Mass effect 3 crash on multiplayer