How to Calculate the Odds of Winning a Raffle

By Carter McBride
Raffle odds
holding winning lottery image by drx from Fotolia.com

Often community or non-for-profit organizations run local raffles to raise money. Usually a person will pay a certain sum of money for a chance to win the raffle. It is possible to calculate the probability of winning a raffle.

Determine the number of chances the person acquired and the number of chances given out. For example, a charity conducts a raffle with 50 tickets. A person buys two tickets. The first two tickets picked will each win a prize.

Determine the outcome your chances of not winning the first drawing. In our example, the outcome chances are two in 50 that charity picks the person's ticket on the first try, express this as a fraction as 2/50, so the probability of not winning is 48/50.

Determine any other chances of your number getting picked in the raffle. In example, after the first person won the raffle, the second picks odds were two in 49, express this as a fraction of 2/49. The probability of not winning is 47/49.

Multiply the fractions of not winning together. In the example, 48/50 times 47/49 equals 0.9024, or 90.24 percent.

Subtract the percent of not winning from 100 percent to determine the odds of winning. In our example, 100 percent minus 90.24 equals 9.76% chances of winning.