Collector tools · Coins
Actual silver weight.
Type in a coin’s weight and its fineness. Get the grams, grains and troy ounces of pure metal inside it, for silver, gold or platinum.
Two numbers that sound alike get mixed up. Fineness is a proportion: the share of the coin that is precious metal. Actual silver weight, ASW, is a mass: how much of the metal there is. A CoinTalk thread opens with a member who saw an auction-site dealer “using the “fineness” or “purity” of an old Mexican coin as the actual amount of silver”. The fix in that thread is one multiplication, and this page does it in any weight unit and any way of writing fineness.
Short answer: pure metal weight = coin weight × fineness. A 1964 US quarter weighs 6.25 g and is 0.900 fine, so it holds 6.25 × 0.900 = 5.625 g of silver. Divide by 31.1034768 g per troy ounce and that is 0.1808 troy oz.
Fineness is a share, ASW is a weight
Wikipedia defines millesimal fineness as a way of denoting the purity of platinum, gold and silver alloys by parts per thousand of pure metal by mass. A coin stamped or described as .900 is 900 parts silver in 1,000. That tells you the proportion and nothing about size. A 6.25 g quarter and a 26.73 g dollar are both 0.900 fine and hold very different amounts of silver. Multiply the coin’s weight by its fineness and you have the mass of the metal itself. Gold works the same way: karats count parts out of 24, so a 14 karat piece is 14/24, or 0.5833.
Which ounce
Precious metal content is usually quoted in troy ounces. NIST Handbook 44 (2026) Appendix C lists the troy ounce as 31.103 476 8 g, which is 480 grains, and the avoirdupois ounce as 28.349 523 125 g. A grain is 0.064 798 91 g. The troy ounce is about 9.7% heavier than the ounce on a kitchen or postal scale, so the unit box matters. If you pick an ounce unit, the result also shows what the other ounce would have given.
Worked example
A US quarter dated 1964 or earlier: 6.25 g × 0.900 = 5.625 g of silver, 86.81 grains, 0.1808 troy oz. A CoinTalk member working the same coin gets “asw of 5.625 grams or .1808 ounces”. A Canadian dollar from 1935 to 1967 weighs 23.33 g and is 0.800 fine: 23.33 × 0.800 = 18.664 g, or 0.6001 troy oz. The thread reports “the correct .600 oz.” for that coin. A Morgan dollar, 26.73 g at 0.900, holds 24.057 g or 0.7735 troy oz, matching the 24.057 g and 0.7734 troy oz Wikipedia gives. For gold, an American Gold Eagle weighs 1.0909 troy oz at 0.9167 fine: 1.0909 × 0.9167 = 1.0000 troy oz.
Reading the result
The answer is how much metal there is, not what it is worth. Melt value is the troy ounces times the metal’s spot price, and the sterling silver and junk silver calculators linked below take that last step. For a worn coin, weigh it: wear removes metal, so a published specification is an upper bound.
What this page does not cover
It does not know a coin’s true fineness. You supply it from a reference or the coin’s markings. Clad and plated coins have no single fineness and are outside what this multiplication describes.
Common mix-ups
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Often assumedAn ounce is an ounce, so a coin described as one ounce weighs the same on a kitchen scale as it does in troy ounces.
What the source saysNIST lists the troy ounce as 31.103 476 8 g and the avoirdupois ounce, the one on kitchen and postal scales, as 28.349 523 125 g. They differ by about 9.7%, so enter the unit you actually read, or use grams. [1]
Checked against these sources on .
Frequently asked questions
What does ASW mean?
Actual silver weight: the mass of pure silver in a coin, usually in troy ounces. The gold version is AGW.
How do I calculate ASW?
Multiply the coin’s weight by its fineness as a fraction. If the weight is in grams, divide by 31.1034768 to get troy ounces.
Why can’t I use fineness as the silver content?
Fineness is a proportion, not an amount. Two coins can share a fineness and differ many times over in size.
Should I weigh in grams or ounces?
Either works if the unit is right. A kitchen scale in ounces uses avoirdupois ounces, which are lighter than troy ounces, so grams are the safer choice.
How do I enter 90% silver or 14 karat gold?
Pick the matching format: 900 parts per thousand, 90 percent, 0.900 decimal, or 14 karats. All four describe a share of the coin by mass.
Does this give melt value?
No. Multiply the troy ounces by the current spot price. The sterling silver and junk silver calculators do that step.
Sources and how it is calculated
Retrieved
The formula is the one the CoinTalk members arrive at after correcting an early post that divided by fineness. Unit constants are from NIST. Coin weights and compositions are from the Wikipedia articles above, all read on 26 October 2026.
- CoinTalk, ““Fineness” is not the actual amount of silver in a coin”: weight multiplied by fineness, with the 1964 quarter and the .800 Canadian dollar worked
- CoinTalk, “How much gold is actually in these?” (page 2): the American Gold Eagle 1.0909 × 0.9167 example
- NIST Handbook 44 (2026), Appendix C: troy ounce 31.103 476 8 g, avoirdupois ounce 28.349 523 125 g, grain 0.064 798 91 g
- Wikipedia, Fineness: millesimal fineness, sterling 925, coin silver 900, karat relation
- Wikipedia, Washington quarter: pre-1965 silver quarter 6.25 g, 90% silver
- Wikipedia, Morgan dollar: 26.73 g, 90.0% silver, 24.057 g and 0.7734 troy oz of silver
- Wikipedia, Canadian silver dollar: 1935 to 1967 circulating dollar 23.33 g, 80% silver
- Wikipedia, Canadian Silver Maple Leaf: 31.11 g, .9999 fine
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Check the numbers for your coin
Fineness and weight come from references or markings, and a worn or altered coin differs from its specification. Treat the result as an estimate of metal content, not an appraisal.