Remember when we all thought "when are we ever going to use this math" while we were in school? Well, here's one of those rewarding chances to do some simple math, yet have it pay you in real dollars. Understanding sports odds is the first essential step in making an informed sports wager.
Step 1: Identify the type of line you are looking at. All online sports books offer you the chance to have your lines in an "American" or "Money line" version. If I were you, I would use this as my standard. An "American" line uses either a + or - before a number to indicate odds. So a -120 and a +120 are two very different odds on a team… I will explain the differences shortly. Two other less common variations exist: decimal odds and fractional odds.
--Fractional odds are most commonly found in racing. A 10/1 payout should be read "$10 paid for every $1 wagered." When the bigger number is on the left, you will find that bet is normally an underdog in the race. Also note, however, that in case such as "Who will win the Super Bowl in the NFL?" you will see all the teams listed as "underdogs"… i.e. paying at least 2/1 (some up to 300/1 or more).
--Decimal odds are largely used in Europe. Essentially, unless you are forced to use these, do not. For 99 percent of bettors today, American/Money Line or Fractional odds will serve much better.
Step 2: Identify the favorite. Lines with a - before the number (i.e. -200) indicate the favorite. A -200 should be read as: "For every $200 wagered, I win $100." When there is a negative sign, the line should always be read with relation to 100. That does not mean you have to bet that much, it's just easiest to understand! When a + sign is present, just reverse the reading, always keeping reference to 100:
1) -150: For every $150 wagered, I win $100 ($50 wagered would win $25).
2) +300: For every $100 wagered, I win $300 ($50 wagered would win $150).
3) 100 (can be either +/-): For every $100 wagered, I win $100 ($50 wagered would win $50).
4) Most commonly: -110: For every $110 wagered, I win $100.
You see "4" most commonly because the extra $10 you have to bet to win $100 is called the "juice" that the books keep as a fee for making the line available to you.
The most important thing you can teach yourself early on is: "Just because the books assign one side to be the favorite (even large, -200 or -300, favorites), does not mean that they will win." We have all seen favorites get upset, and it is important to avoid the temptation of finding comfort in the fact that the lines makers put one team as a favorite.