Sports Betting

Last update: May 23, 2008

Sports books have to cram a lot of information on a limited amount of space. To save space they generally just throw up the numbers and you are supposed to know what they mean. Let's look at an example.

• The -7 is the point spread. This is for use in point spread bets (see below).
• The 44 is the total. This is for use in total bets (see below).
• The +260 and -320 are money lines. These are for use in money line bets (see below).

Unlike horse racing bets the winner of a sports bet always gets his original bet back if he wins.

I admit "point spread bet" is not a common term in sports betting, but I'm trying to change that. What I call a point spread bet is a basic bet against the point spread. Many people call this a "straight bet" but this term can also be used, and is printed on tickets for, money liney bets, total bets, and any other bet involving just one game. So I invite the rest of the world to adopt this term.

In the example above Green Bay is favored to win by seven points. So two Point Spread Bets would be available on this game: (1) that Green Bay wins by 8 or more points, and (2) Giants win or lose by 6 or fewer points. Generally the point spread is next to the favored team and is thus a negative number.

Usually with a Point Spread Bet the bettor must risk $11 to win $10, or any proportion therein. Sometimes if the action is lopsided, or predicted to be lopsided, the sportbook will make you bet more on the favored side and less on the other. Let's look at the following example.

     Washington Redskins -3 EV
     Cleveland Browns +3 -120
     

In this example a point spread beat on Washington would pay even money and on Cleveland the bettor would risk $12 to win $10, or any proportion therein.

Point Spread Bets are commonly found in high scoring games, namely football and basketball. Assuming a 50% chance of winning, laying $11 to win $10, and ignorring ties, the house edge is 4.54%. Sometimes a casino will have a happy hour promotion in which the bettor must only risk $10.50 to win $10. In this case the house edge drops to 2.38%.

In the NFL home underdogs have historically done well against the spread. Here are the raw results of all 6167 NFL games played from the 1983 through the 2007 season.

• Home team favored, favorite wins against spread: 1674
• Home team favored, underdog wins against spread: 1762
• Home team favored, tie against spread: 49
• Visiting team favored, favorite wins against spread: 737
• Visiting team favored, underdog wins against spread: 836
• Visiting team favored, tie against spread: 88

The following table shows the probability of winning, losing, and drawing according by various breakdowns. The house edge column is assuming a bet of $1.10 to win $1.00. Note that bets on home dogs over the sample period would have resulted in a player advantage of 0.18%, laying -110.

For more on betting home underdogs I recommend Sharp Sports Betting by Stanford Wong. Also visit my sports betting appendix 2.

Total Bets are similar to point spread bets, except the bettor bets on the total points scored. In the example above the bettor bets whether the total points combined between the Giants and Green Bay will be over or under 44. Like point spread bets the bettor must generally risk $11 to win $10, for a house edge of 4.54%.

Following are the result of 5198 NFL games from from Sept 4, 1983 to Nov 15, 2004, in which I have the total line.

• Over wins: 48.23%
• Under wins: 50.13%
• Game ends exactly on total: 1.64%

Overall the house edge on over bets is 6.92% and on unders is 2.92%, assuming the bettor risks $11 to win $10.

Money Line bets are simply on whom will win. In the example above the +260 for the Giants means that a $100 bet on the Giants would win $260, or any proportion therein, if the Giants won the game. The point spread in Green Bay is -320, which means that the bettor must risk $320 to win $100.

Unlike point spread and total bets sportbooks vary on how good their money line bets are. In general the further apart the two lines are the greater is the house edge. I don't have any historical money lines but I will say in my very strong opinion it is better in general to bet on underdogs than favorites against the money lines.

For more about money lines visit my sports betting appendix 3.

The Parlay is a way to bet on multiple sporting events with hope for a big payoff if all of them win. With parlay cards, all picks are relative to the point spread. If just one event doesn't win or draw then you lose the entire bet. If one or more event is a draw then those events are ignored. If you win all the other events you get paid according to the number of events that you did win. In the event all games bet on result in a push except one or none then the entire bet becomes a push. The following table shows the house edge for various number of picks and pays assuming a random picker.

Parlay bets can be done "against the board" or "against the card." Against the board the bettor goes up to the window and states his picks and the point spread on the board is used. Against the card the bettor fills out a 4.25" by 11" colored card with his picks against the point spreads stated on the card. For the recreational gambler if you must make a parlay bet I recommend going off the board. However parlay cards can be exploited to a degree by picking events in which the line on the board has moved in your favor relative to the card, especially against the critical 3 and 7 point margins of victory in football.

Following are the general formulas for the house edge according to the number of picks. The "win" is are payoff odds.

• Pick 2: (3-win)/4
• Pick 3: (7-win)/8
• Pick 4: (15-win)/16
• Pick 4: (31-win)/32
• Pick 5: (63-win)/64
• Pick 6: (127-win)/128
• Pick 7: (255-win)/256
• Pick 8: (511-win)/512
• Pick 9: (1023-win)/1024
• Pick 10: (2047-win)/2048
• Pick 20: (1048575-win)/1048576

The Golden Nugget used to have a "$1,000,000 Parlay Card", which paid $1,000,000 for a $5 bet, or 200,000 for 1. For a random picker this carries an 80.93% house edge (ouch!).

The bettor can combine any bets he wishes when making an "off the board" parlay bet, unless the sport book deems the events to be correlated. If all events chosen are -110 the win will be according to a set pay table, like 13 to 5 for a 3-team parlay. If just one event is not -110 then a mathematical calculation will be performed to determine he winning odds. That calculation is to take the product of the winning odds each event, on a "for one" basis. That will result in the winning odds on a "for one" basis. Let's look at an example. Suppose in a $5 four-event parlay the off the board odds are -110, even money, +125, and -400. The winning odds, on a "for one" basis, on each event are 210/110, 2, 2.25 and 5/4, respectively. The parlay will pay $5 × (210/110) × 2 × 2.25 × (5/4) = $53.69 if it wins. Sometimes the actual win will be slightly off from what you get using this method. The reason, I believe, is due to rounding error at each step in the calcultion by the sports book.

Teasers are similar to parlays except the point spread on each game moves 6, 6.5, or 7 points in the player's favor. The player pays for this in the form of much lower winnings. For example in the Giants/Green Bay example if you teased Green Bay then they would cover the tease as long as they won by at least one point.

In general teasers are a sucker bet with a house edge of 9% to 43%. However if you can cross both the 3 and the 7 point margin of victories then 6-point NFL teasers can become a good bet. This would include 7.5 to 8.5 favorites and 1.5 to 2.5 underdogs. For more on this play I recommend Sharp Sports Betting by Stanford Wong. For more on teasers in general please visit my sports betting appendix 4.

Futures are a bet on who will win the championship when there are still more than two possible teams to bet on. The house edge on futures varies substantially from one sportbook to another. However in general they are a sucker bet and to be avoided. For information on who does offer the best futures in Las Vegas visit my sports betting appendix 5.

    See important note about Bodog payouts & deposits.