All U.S. nickels (5-cent pieces) minted since 1965 weigh 5.0 grams (0.176 ounces). U.S. nickels have a diameter of 21.21 mm, a thickness of 1.95 mm, and are composed of copper (75%) and nickel (25%).
The U.S. government first proposed a nickel in the Coinage Act of 1792. The first nickel was called a “half disme” and was 1.20 grams (0.042 ounces). It was struck of 89.25% silver and 10.75% copper.
From 1796 to 1803, the US minted the Draped Bust half dime (nickel), which increased the weight to 1.35 grams (0.047 ounces). In 1829, the Capped Bust nickel was issued, which reduced the weight back down to 1.20 grams. From 1837 to the Coinage Act of 1873, the metallic content was changed to 90% silver, 10% copper, and the weight varied from 1.34 grams (0.047 ounces) to 1.24 grams (0.043 ounces). From 1866 to 1883, the US also issued “Shield” 5 cent pieces that used 75% copper, 25% nickel, as silver was more difficult to come by during the Civil War. The weight was also upped to 5 grams. Following the civil war, the weight remained at 5 grams, while the metallic composition was normalized to the copper/nickel mix.