As of October 2015, the value of the silver content in a 1964 U.S. Kennedy half dollar is $5.83. Silver trades at $16.11 per ounce, a Kennedy half dollar contains 90 percent silver, and the weight of the coin is 12.5 grams.
The U.S. Mint only produced Kennedy half dollars in 1964. However, the half dollars that it produced between 1916 and 1963 also contain 90 percent silver, and so they are worth the same amount as a 1964 Kennedy half dollar. The half dollars produced between 1965 and 1970 contain only 40 percent silver, and so they are worth only $2.39 as of October 2015.