Most coins in a jar are worth face value. The ones that are not usually give themselves away through a handful of clues you can check at the kitchen table in a few minutes. Work through these seven steps in order.
1. Read the date and the mint mark
Everything starts with the date and the small mint-mark letter near it. The same year can be common from one mint and scarce from another: the 1909-S VDB cent had a mintage of 484,000 while the 1909 VDB from Philadelphia had nearly 28 million. A coin with no mint mark was usually struck in Philadelphia. Use a 5x to 10x magnifier and good light and see our mint mark guide for where to look on every series.
2. Check the metal: silver sets a floor
Any US dime, quarter or half dollar dated 1964 or earlier is 90% silver and Kennedy halves dated 1965 to 1970 are 40% silver. Nickels dated 1942 to 1945 with a large mint mark above Monticello contain 35% silver. A single 90% silver quarter holds 0.1808 troy ounces of pure silver, so its value never falls below that much silver at the day's price. The quickest test is the edge: a clad coin shows a copper stripe, while a silver coin's edge is solid silver-white. Our silver coin chart lists every silver issue.
3. Compare the mintage
Mintage, the number of coins struck, is the first rough measure of rarity. Each coin page on WePlayCoins shows the mintage and where it ranks within its series. Anything under about half a million struck for circulation is scarce by almost any standard; under 50,000 is genuinely rare. Survival matters too: some high-mintage dates were melted in bulk and are scarce today in top condition.
4. Look for errors and varieties
Errors are mistakes in the minting process; varieties are differences between dies. The famous ones carry a collector premium or more:1943 bronze cents, 1944 steel cents, the 1955 doubled die cent and the 1922 "No D" cent. Under magnification, look for doubled letters and numbers, repunched or missing mint marks, off-center strikes and coins struck on the wrong metal. Damage after the coin left the Mint, such as scratches, dents or plating, is not an error and adds no value.
5. Judge the condition honestly
Condition, or grade, can multiply value many times over for the same coin. Collectors use a 70-point scale where 60 and above means the coin has never circulated. Look at the highest points of the design: if the details are flat and smooth, the coin is worn. Our grading basics guide explains each step of the scale.
6. Do not clean it
Cleaning is the most common way people destroy a coin's value. Polishing, dipping or rubbing leaves fine scratches and an unnatural shine that any dealer will spot immediately and grading services label such coins as "details: cleaned". Store the coin as it is. See how to store coins safely.
7. Find a real market price
Price guides are a starting point, but the best evidence is what identical coins actually sold for recently. Search completed auction results for the same date, mint mark and grade and compare certified coins with certified coins. For anything that looks like it could carry a collector premium, have it authenticated and graded by a major service such as PCGS or NGC before selling. It protects both you and the buyer and valuable dates are the most counterfeited.
Start your search: try a year and mint mark in the search box above, or browse the key dates and errors list.
False alarms that fool beginners
Many coins that look unusual are not errors at all. Machine doubling, a flat shelf-like doubling caused by a loose die bouncing after the strike, is far more common than a true doubled die and carries no premium. Gold-colored State quarters and Presidential dollars are usually plated after leaving the Mint. Coins with odd colors have often been heated or exposed to chemicals. A coin that is bent, squeezed or has a missing piece with a jagged edge was almost always damaged in circulation. A genuine clipped planchet has a smooth curved edge and weak rim detail opposite the clip.
What to do once you think you have something
Put the coin in a soft non-PVC flip or a cardboard 2x2 holder right away, handling it only by the edge. Photograph both sides in diffused light, then compare it with the diagnostics on the coin's own page here: the shape of the doubling, the position of the mint mark or the exact die markers. Weigh it if you have a scale. Write down where and when you found it. If it still looks right, ask a dealer or a local coin club for an opinion before paying for professional grading.
Frequently asked questions
How can I tell if my coin is a real error or just damaged?
Errors happen during striking, so the metal flows smoothly and the rest of the coin looks normal. Damage after striking leaves scrapes, dents, flattened letters or raised burrs.
Is a doubled-looking date always a doubled die?
No. Most doubling seen on coins is machine doubling, which looks flat and shelf-like. A true doubled die shows rounded, separated second images.