Most amateur bowling leagues and tournaments utilize a bowling handicap system. Your bowling handicap allows you to compete against other bowlers with varying levels of skill and ability with a better chance of being competitive. A bowling handicap is a percentage of the difference between your average and a basis average. Subtract your average score from the basis score and multiply the result by the percentage factor to calculate your bowling handicap. The basis score is 230 and the percentage factor is 90 percent. If your average is 147, you have (230-147) X 0.90 = 74.7. Again, drop the fraction. Your handicap in this example is 74 pins per game. Add the handicap to your actual score for each game. For instance, if you have a game in which you score 160 and your handicap is 74, your adjusted score is 234.