You will notice that as wagering on a race progresses closer to post time, the odds will change. Why is that you ask? The Cash that is wagered in a horse race is counted up and put into Pools. What is a Pool? A Pool is where the total amount of money that is wagered on a specific type of bet is held to be redistributed to patrons that have correctly selected the outcome of the specific wager they have placed. Out of these pools certain percentages are subtracted. The Government receives a percentage (taxes) for allowing the race in a certain jurisdiction. The Racetracks receive a percentage for promotions, maintaining the racetrack, and paying employees. The horsemen receive a percentage that makes the Race Tracks able to offer purse money to the owners and trainers for racing horses. If there was no money, there would be no racing. After the percentage is removed, the remaining money is paid out. This is where gamblers get their payouts for winning tickets.
The odds are usually in the form of x/y (e.g. 5/1, 9/5). Dividing x by y gives a ratio to 1. The smallest ratio or the largest amount of money on a number represents the favorite.
Winning odds of 2/1 will pay $6.00 for a $2 bet, while 5/1 will pay $12.00 for a $2 bet. Payout is calculated by (odds ratio to 1) x bet amount + bet amount.
Example: For odds of 5/1, the approximate payout for a $2 bet is 5 x $2 = $10 + $2 = $12.
Some tracks allow different minimum amounts on each type of bet; generally, $1 bets tends to be the minimum on all bets. The offshore sportsbook odds are calculated based on the sales for the bet minus a government, and handling tax. These deductions vary and are usually controlled by a regulatory body. Deductions may vary in the same track if there are simulcast races. In addition some tracks tax payouts in excess of a specified limit; generally, this limit is 600/1.