This MLS playoff magic numbers matrix is created dynamically from the MLS Standings at the MLS website. If you're curious about the technical details, check out the semi-detailed info on how this tool works.
The primary use for magic numbers is to determine roughly what combination of wins, losses, and ties are needed for a team to make it into the playoffs. I say roughly, because tiebreakers can make things complicated. To use the matrix to the left, first select a team of interest from the leftmost column. As you scan across the row to the right, you will see the magic numbers for your chosen team against all the other teams.
The magic number for Team A against Team B is the maximum number of points Team B can end the season with minus the current number of points for Team A. The lower the magic number for Team A against Team B, the closer Team A is to guaranteeing they will finish the season above Team B.
Negative magic numbers are meaningless, so I replaced them with a '-'. If you see a '-', that means the lower placed team cannot catch the higher placed team, no matter how many games either team wins or loses. If a team's magic number is so high against another team that they can't catch them, the magic number is replaced with a '+'.
Here's an example. As of August 24, 2003, San Jose's magic number with Dallas was 3 and with Los Angeles was 13. San Jose will be guaranteed to finish above Los Angeles in the final standings if the combination of the points that San Jose picks up and the points that Los Angeles does NOT pickup by the end of the season exceeds 13.
San Jose's magic number against LA decreases with a San Jose win (by 3 points), San Jose tie (by 1 point), LA loss (by 3 points), or LA tie (by 2 points). In the regular standings, you don't lose points for a loss. In the magic numbers matrix, you do, though, because a loss means another 3 potential points are no longer attainable to help you close the gap with the teams in front of you. A tie costs the lower placed team two points, since the team got only 1 out of a possible 3 points.
Since only one team from each conference doesn't make the playoffs, San Jose needs only to get their magic number below 0 with at least one team. If a magic number is exactly 0, you have to look at the tiebreaker rules to determine who would finish ahead if the season were to end with those two teams having the same number of points.
So, if San Jose wins one of their remaining matches, they will definitely finish at least even with Dallas, no matter how many games Dallas wins. Similarly, if Dallas loses a match, San Jose will finish at least even with them, even if San Jose loses every remaining match. In this example, since San Jose has already won 3 of their 4 head-to-head matches, San Jose would finish ahead of Dallas if somehow they ended up even on points.