Different states in the US hold different laws related to car horns. Some states even have laws on the limit of acceptable decibels on the car horns. The general car horn range on automobiles that you can carry in the United States is between 100 decibels to 150 decibels. However, in some states, it is just limited to 120 decibels. You can always look up for your state’s DMV to know the legal limit to ensure you do not get fined.