Numistify guide
Error Coins: What They Are and How to Spot Them
Error coins are real, and a few are valuable. Most coins that look odd in pocket change, though, are common striking flukes or damage done later. Here is how to tell the difference.
The short answer
An error coin was made incorrectly at the mint — an off-center strike, a clipped planchet or a doubled die, for example. Damage done after a coin left the mint is not an error and adds no value, and machine doubling, which is very common, is not a doubled die.
What counts as an error
An error coin is a coin the mint made incorrectly. Some errors happen to a single coin during striking; others come from a flaw in the die and repeat on every coin it struck — collectors call those varieties. Damage that happens after a coin leaves the mint is not an error at all.
Two cautions before you start. Being unusual does not make an error valuable: off-center strikes, for example, are unique individually but not extremely rare as a group. And the famous errors are counterfeited, so a valuable-looking error deserves expert confirmation.
The main types
Doubled die. The die itself was made with a doubled image, so every coin from it shows doubled letters or numbers.
Off-center strike. The blank was not centered in the press, so part of the design is missing and part of the coin is blank.
Broadstrike. The coin was struck outside the retaining collar, so it spread out wider and thinner than normal, with no proper edge.
Clipped planchet. The blank was cut incorrectly from the metal strip, leaving a curved or straight piece missing from the edge. A genuine clipped coin weighs less than a normal one.
Die crack and cud. A crack in the die prints as a raised line; a broken piece of die leaves a raised blob, called a cud, usually at the edge.
Strike-through and filled die. Debris or grease in the die leaves part of the design missing or weak. The 1922 “No D” cent is the best-known example.
Lamination and split planchet. A flaw in the metal causes peeling or a split surface.
Missing plating. Modern US cents are copper-plated zinc; occasionally the plating is incomplete or missing.
Doubled die or machine doubling?
This is where most people go wrong. A true doubled die shows rounded, clear secondary images, and the same doubling appears on every coin from that die. Machine doubling (also called strike doubling) happens during striking: it looks flat and shelf-like, it is very common, and it adds no value. Worn or deteriorating dies can also produce doubling-like effects. If the doubling looks mushy or flat, it is almost certainly not a doubled die.
Damage that fools people
Coins pick up damage after leaving the mint — collectors call it post-mint damage — and it can look like an error. A “clip” with a jagged or fresh-looking edge is usually damage, not a clipped planchet. Coins that are bent, plated, discolored by heat or chemicals, or squeezed thin are damaged, not errors. Weighing a coin helps: a clipped planchet weighs less than normal, while many altered coins do not.
Famous examples
1955 doubled die Lincoln cent — strong doubling on the date, LIBERTY and IN GOD WE TRUST, visible without magnification. Also widely counterfeited.
1969-S, 1972 and 1995 doubled die cents — later doubled dies that collectors look for in change and rolls.
1922 “No D” cent — only Denver struck cents in 1922, so a 1922 cent with no mint mark is a known filled-die error.
1942/1 Mercury dime — an overdate, with a 2 struck over a 1.
How to check a coin you think is an error
Use magnification and good light, and compare with photographs of confirmed examples.
Weigh it on an accurate scale and compare with the standard weight.
Ask whether it could be damage before assuming it is an error.
Research the value in references such as the Red Book, auction records and eBay sold listings for the same error, and show it to your local coin shop.
Consider authentication for anything valuable; PCGS and NGC attribute errors and varieties. See how to send coins for grading.
Questions people ask
What is an error coin?
A coin made incorrectly at the mint, such as an off-center strike, a clipped planchet or a doubled die. Damage that happens after a coin leaves the mint is not an error and adds no value.
How can I tell a doubled die from machine doubling?
A true doubled die was created in the die itself, so the doubling is rounded and repeats on every coin from that die. Machine doubling happens during striking, looks flat or shelf-like, is very common and adds no value.
Are off-center coins valuable?
Some are, depending on how far off-center they are and whether the date shows, but off-center strikes are not extremely rare. Being unique does not by itself make an error valuable.
What is the most famous error penny?
The 1955 doubled die Lincoln cent, with strong doubling on the date, LIBERTY and IN GOD WE TRUST that can be seen without magnification. It is also widely counterfeited.
How do I find out what my error coin is worth?
Compare it with auction records and eBay sold listings for the same error, check a reference such as the Red Book, and show it to your local coin shop. Valuable errors are usually worth authenticating through a grading service.
Related guides
How to tell if a coin is valuable — errors among the other signs of value.
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