What are Pennies Made Of?

You may think all pennies are made of solid copper, but many are copper-plated zinc. There are several ways to tell the difference, one of which is knowing when the United States switched from all copper pennies to zinc-plated cents.

In the early 1970s, the rising price of copper pushed the cost to make a penny over its face value of one cent. Fortunately, the price of copper dropped and production continued. Unfortunately, the increasing price of copper in the early 1980s forced The United States Mint to change the penny's composition permanently to prevent a melt-off of pennies. In the United States' past, when the melt value of a coin exceeded its face value, people would often melt the coins to sell the raw metal and make a profit.

To thwart a melt-off of pennies in 1982, the United States Mint made half of the cents out of solid copper and the other half out of copper-plated zinc. Although it is illegal to melt pennies and sell the raw metal, people still pull the solid copper pennies out of circulation to save them for their copper value.

For pennies dated 1982, when the U.S. made copper and copper-plated zinc coins, weighing them is the best way to determine their composition. Solid copper pennies weigh 3.11 grams (+/- 0.130 g.), whereas the copper-plated zinc cents weigh only 2.5 grams (+/- 0.100 g.).

If you have a Lincoln Memorial penny with a date before 1982, it is made of 95% copper. If the date is 1983 or later, it is made of 97.5% zinc and plated with a thin copper coating.

The Best Way to Tell the Difference

Be sure to use a scale that is accurate enough to detect a tenth of a gram (0.1 g.) or better. If you weigh a zinc penny on a scale that can only register full 1-gram increments, the penny will usually display 3 grams since the scale rounds the 2.5-gram zinc penny upwards to 3. The wrong type of scale can be misleading when you are trying to sort copper and zinc pennies.

Drop Test for Copper and Zinc Pennies

If you don't have a tenth-gram scale handy, use the "drop" test. You need a hard Formica or granite countertop surface, a known copper penny, and a known zinc penny. Drop each one onto the table, listening to its distinctive sound. Zinc pennies have sort of a flat "clunk," whereas copper pennies have a higher-pitched, more melodic "ring" sound.

Once you have a good feel for how each type sounds, start dropping your 1982s one at a time and listening to the sounds they make. You should be able to sort them out by metal composition. Obviously, this test isn't as reliable as weighing them, but it should help you sort most copper and zinc pennies.

Cherrypicker's Tip

Watch out for "transitional" mint errors! "Transitional" errors occurred in the Lincoln Memorial Cents series when the Mint accidentally used solid copper blanks to make a few pennies in 1983. These "wrong stock" pennies weigh 3.11 grams, rather than the 2.5 of the copper-plated zinc cents. If you find a solid copper 1983, it might be worth a pretty penny! Take it to a trusted local coin dealer to verify your findings.

In 2006, numismatist Billy Crawford was searching through rolls of pennies. He individually weighed all the 1983-dated pennies. All of them returned a value of 2.5 g until one weighed in at 3.11 g. At this point, he knew that he found a solid copper penny dated 1983 that should be made of copper-plated zinc. In 2013, a 1983 copper Lincoln Cent graded PCGS Mint State 62 Red-Brown sold for $23,500 through Heritage Auctions. In 2015, Stack's Bowers sold a PCGS Mint State 62 Brown example for $22,325.