Oil mix charts provide the ratio of gasoline to oil that is optimal for each engine. For example, a required mixture of 32:1 would mean 32 parts gasoline to 1 part oil. The correct amount of oil (in ounces) would be equal to ounces of gasoline used divided by 32.
The correct ratio of gasoline to oil can be found in the owner's manual of the equipment. Never attempt to mix gasoline and oil directly in the equipment's fuel tank. Always mix beforehand in a separate container. Free calculators can be found online to simplify the process of finding the correct amount of oil needed.