Penny Metal Composition by Year:

1793-1837 - Pure copper.

1837-1857 - Bronze (95% copper, 5% mixture of tin and zinc).

1857-1863 - 88% copper, 12% nickel.

1864-1962 - 95% copper, 5% zinc (trace amounts of tin).*

1962-part1982 - 95% copper, 5% zinc (no tin).

part1982-present - 97.5% zinc, 2.5% copper (copper plated).**
 
 
*exception 1943 - pure steel, zinc-coated with rare 1943 error copper minted pennies.
 
**exception 1983 - rare 1983 error copper minted pennies.