Interactive · The Coin Cellar
Is my coin fake? Check its weight and size
A genuine American Silver Eagle weighs 31.103 grams, is 40.6 millimeters wide and about 2.98 millimeters thick. A fake made of cheaper metal can’t match all three, because the copper alloys fakes are made of are lighter than silver: get the weight right and the coin comes out too big; get the size right and it comes out too light. Weigh your coin on a scale that reads to 0.01 gram, measure it with calipers, and type the numbers below. The checker compares them with the published specification for 20 silver and gold coins.
Coin weight and size checker
Set the scale to grams.
Edge to edge, across the middle.
Measure at the rim, the thickest point.
Leave a box empty if you can’t measure it. Nothing you type leaves your browser.
American Silver Eagle · 30.60 g, 39.90 mm wide
This doesn’t match a real Silver Eagle.
30.60 gmint spec 31.103 g−0.50 g (−1.6%)
39.90 mmmint spec 40.6 mm−0.70 mm
—mint spec 2.98 mm
The mint and this coin disagree, and the mint wrote the specification. It is light for a Silver Eagle. A new bullion coin should not lose metal, so this is either a lighter metal or a bad scale. (These are the readings of a fake 2000-P Silver Eagle that NGC examined in 2020. Type in your own.)
How this is worked out
- 1. Each reading is compared with the coin’s published specification, listed in the table below with its source.
- 2. Weight within 0.5% of the spec matches; within 1.5% is close; further out is off. On a Silver Eagle, 0.5% is 0.16 grams.
- 3. Width within 0.25 mm matches, within 0.5 mm is close. Thickness within 0.2 mm matches, within 0.4 mm is close.
- 4. Old circulated coins (US 90% silver, sovereigns, Saint-Gaudens) may read up to 3% light and still count as normal wear. Wear never excuses a coin that reads heavy.
These bands are our choice, not a mint tolerance. Mints don’t publish tolerances for most of these coins. We set the bands wide enough that a careful reading of a real coin passes, and narrow enough to catch the fakes NGC has published. A wrong-metal fake at the right weight comes out about 20% bigger by volume, far outside any band here. Thickness is the loosest of the three because published figures for the same coin differ by a tenth of a millimeter or more, and where we could not find two sources that agree, the checker skips it. Data updated October 2026: every specification checked against the sources below.
Worked examples
- A fake 2000-P Silver Eagle that NGC examined weighed 30.6 grams and was 39.9 mm wide. That is 0.50 grams (1.6%) light and 0.70 mm narrow: off on both counts.
- A fake 2023 Silver Eagle weighed 31.54 grams, 1.4% heavy. The checker calls that close, not off, and NGC treated it the same way, as a warning. What gave it away was its thickness: NGC called it “much too thick.”
- A worn 1921 Morgan dollar at 26.20 grams is 2.0% light. For a coin that spent a century in pockets, that reads as normal wear.
- A Silver Maple Leaf at 31.11 grams, 38.0 mm and 3.29 mm matches on all three, which is as far as a scale and calipers can take you.
How much should a silver coin weigh? The specifications
The weight, width and thickness of a new coin of each type. Where the thickness column says “not checked,” published figures disagree and the checker doesn’t test it.
| Coin | Weight | Width | Thickness |
|---|---|---|---|
| Silver bullion, 1 oz | |||
| American Silver Eagle | 31.103 g | 40.6 mm | 2.98 mm |
| Canadian Silver Maple Leaf | 31.11 g | 38.0 mm | 3.29 mm |
| Silver Britannia (2013 on) | 31.21 g | 38.61 mm | 3.0 mm |
| Austrian Silver Philharmonic | 31.103 g | 37.0 mm | 3.2 mm |
| Mexican Silver Libertad (1996 on) | 31.1 g | 40.0 mm | 3.0 mm |
| US 90% silver | |||
| Morgan dollar (1878–1921) | 26.73 g | 38.1 mm | 2.4 mm |
| Peace dollar (1921–1935) | 26.73 g | 38.1 mm | 2.4 mm |
| Trade dollar (1873–1885) | 27.22 g | 38.1 mm | not checked |
| Walking Liberty half (1916–1947) | 12.5 g | 30.63 mm | not checked |
| Franklin half (1948–1963) | 12.5 g | 30.61 mm | not checked |
| Kennedy half, 1964 | 12.5 g | 30.61 mm | 2.15 mm |
| Washington quarter (1932–1964) | 6.25 g | 24.26 mm | 1.75 mm |
| Mercury or Roosevelt dime (to 1964) | 2.5 g | 17.91 mm | not checked |
| Gold | |||
| American Gold Eagle, 1 oz | 33.931 g | 32.7 mm | 2.87 mm |
| Krugerrand, 1 oz | 33.93 g | 32.77 mm | 2.84 mm |
| American Gold Buffalo, 1 oz | 31.108 g | 32.7 mm | 2.95 mm |
| Canadian Gold Maple Leaf, 1 oz | 31.11 g | 30.0 mm | not checked |
| Austrian Gold Philharmonic, 1 oz | 31.103 g | 37.0 mm | 2.0 mm |
| British gold sovereign | 7.98 g | 22.05 mm | 1.52 mm |
| $20 Saint-Gaudens double eagle | 33.436 g | 34.1 mm | 2.41 mm |
Weights are the whole coin, not just the silver or gold in it. A Gold Eagle weighs 33.931 grams because it is 22-karat: one ounce of gold plus some copper and silver to make it harder.
Why weight and size together catch fakes
Silver is heavy for its size: 10.5 grams per cubic centimeter. The copper alloys most counterfeiters use are lighter. Nickel silver, the copper, nickel and zinc alloy under most plated cutlery, is about 19% lighter for the same volume. So a counterfeiter has to pick one of two problems.
Make the fake the right size, and it weighs about 19% too little: a nickel-silver “Silver Eagle” the size of a real one would weigh about 25 grams. Any scale catches that. Make it the right weight instead, and it has to take up about 24% more room. Keep the width right and all of that goes into the thickness, which grows from 2.98 to about 3.7 millimeters. Calipers catch that.
Most fakes split the difference: a little light, a little big, a little thick. That is why the checker wants all three numbers, and why each one you add makes the result harder to fool. A coin that is only slightly off on one measurement is a reason to measure again. A coin off on two is a reason to stop and test it properly.
What a scale and calipers can’t catch
Matching numbers mean nothing here argues with the mint. They don’t mean the coin is genuine, and there are three gaps worth knowing.
- Gold-plated tungsten. Tungsten weighs 19.25 grams per cubic centimeter and gold 19.3. A tungsten core with a gold skin can match a real coin’s weight and size almost exactly. For gold, the next step is a ping test or a dealer’s electronic verifier, which reads below the surface.
- Fake dates in real metal. If a coin is worth more than its metal because of a rare date or mint mark, the forger can strike it in real silver or gold. It passes every metal test and is still a fake. That is a job for a grading service, not a scale.
- Worn coins. A circulated coin is lighter than new, so the checker allows old coins up to 3% light. A clever fake could hide inside that allowance, which is one more reason to measure the width and thickness too.
What you need: a scale, calipers, and one known coin
A pocket scale that reads to 0.01 gram and a pair of digital calipers are enough for everything on this page. A kitchen scale that reads whole grams is not: the fake 2000-P Eagle was half a gram light, which a kitchen scale rounds away.
Before you trust any reading, check the scale. A modern US nickel is made to weigh 5.00 grams, so put one on the scale and see what it says. If it reads 4.96 or 5.04, your scale is off by that much, and every coin you weigh will be too.
For the full set of home tests, including the magnet, the ice cube and the specific-gravity test that needs only a cup of water, read the guide how to tell if silver is real.
Questions people actually ask
How much should a Silver Eagle weigh?
A genuine American Silver Eagle weighs 31.103 grams, which is one troy ounce of 99.9% silver. It is 40.6 millimeters wide and about 2.98 millimeters thick. On a scale that reads to 0.01 gram, a new Eagle should read within a few hundredths of a gram of 31.10.
Can you tell if a coin is fake by weighing it?
Weight alone catches many fakes but not all, because a counterfeiter can make a coin of cheaper metal at the right weight by making it bigger. Weigh it and measure its width and thickness. The copper alloys most fakes are made of are lighter than silver, so a fake can match the weight or the size, but not both.
How accurate does my scale need to be?
Use a scale that reads to 0.01 gram. A kitchen scale that reads whole grams can't see the half-gram gap that gave away a fake 2000-P Silver Eagle. Check the scale first with something of known weight: a modern US nickel is 5.00 grams.
Why does my old silver coin weigh less than it should?
Wear. A coin that circulated for decades loses a little metal every time it rubs against other coins, so a worn Morgan dollar or silver quarter can read one or two percent light and still be genuine. Wear only takes metal off, so an old coin that reads heavy is a stronger warning sign than one that reads light.
Is a coin genuine if its weight and size match?
Not necessarily. Matching measurements are consistent with a genuine coin, not proof of one. Gold is the big gap: tungsten is almost exactly as dense as gold, so a gold-plated tungsten fake can match a real coin's weight and size. A collector coin can also be struck in real silver and still be a fake date.
What is the most counterfeited silver coin?
In a 2018 poll of American dealers by the Industry Council for Tangible Assets, 43.3% said customers had tried to sell them counterfeit Silver Eagles, the highest share for any bullion coin. Popular coins get copied most because they are easiest to sell.
What should I do if my coin fails the check?
Measure again, and check your scale with a coin of known weight. If it still fails, don't sell it on to anyone as genuine. A local coin shop can usually test it, and the grading services NGC and PCGS authenticate coins for a fee.
How do you measure the thickness of a coin?
Use digital calipers and close the jaws on the rim, the raised edge around each face, which is the thickest part of the coin. Take two or three readings at different points around the rim and use the largest.
Where the specifications come from
- Silver Eagle: width from the US Mint; weight and thickness from Numista.
- Silver Maple Leaf: Numista and the Royal Canadian Mint.
- Silver Britannia: width from the Royal Mint; weight and thickness from Wikipedia, Britannia (coin).
- Silver and Gold Philharmonic: Wikipedia, Vienna Philharmonic (coin). Silver Libertad: Wikipedia, Libertad (coin), which notes the coins from 1982 to 1995 were narrower and thicker.
- Morgan dollar, Peace dollar, silver quarter and silver dime: Numista (Morgan, Peace, quarter, Roosevelt dime). Numista gives the silver dime as 1.1 mm thick and the US Mint gives today’s dime as 1.35 mm, so the dime’s thickness is not checked.
- Trade dollar (420 grains, which is 27.22 grams): Wikipedia, Trade dollar. Walking Liberty and Franklin halves: Wikipedia and Wikipedia. Kennedy half: Wikipedia and the US Mint’s half-dollar specification.
- Gold Eagle, Krugerrand, Gold Buffalo and Gold Maple Leaf: Wikipedia (Gold Eagle, Krugerrand, Buffalo, Gold Maple Leaf).
- Sovereign: weight and width from the Royal Mint; thickness from Wikipedia, Sovereign. Saint-Gaudens $20: 516 grains (33.436 grams), the legal standard for the double eagle; width and thickness from Wikipedia.
- The two fakes: NGC, “Counterfeit Detection: 2000-P American Silver Eagle” (June 28, 2020) and “Counterfeit Detection: 2023 Silver Eagle” (June 13, 2023). Dealer poll: CoinWeek, June 28, 2018.
- Densities: silver, gold and tungsten (Wikipedia); nickel silver from makeitfrom.com, alloy C75200. The nickel’s 5.00 grams: the US Mint’s coin specifications.
Specifications read October 17, 2026. Worked out by us from them: the 19% and 24% figures, the 25-gram and 3.7-millimeter nickel-silver Eagle, and every difference in the worked examples.