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To participate in the forum you must log in or register. | Author |
 Replies: 8 / Views: 271 |
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Valued Member
Canada
72 Posts |
The following link points to a table in the US Coin Facts reference area. I couldn't tell what the source of the data was for the table. It seems like it might be from the US mint but I couldn't be sure. Is the original source known? https://www.coincommunity.com/us_co...lerances.asp |
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Forum Dad
 United States
24148 Posts |
Various sources, but mostly the Mint.
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Moderator
Australia
16808 Posts |
Coinage tolerances are ultimately derived from government legislation. Each of the tolerances can usually be found in the various pieces of legislation that authorize those specific coins. The current tolerances for the penny and nickel, for example, reside in 31 USC 5113. Unfortunately, these figures aren't all codified in one central piece of legislation, but scattered about the current and historic body of law. Since it's the Mint's job to actually make the coins and adhere to the various standards applicable for those coins under law, it's been the Mint's job to collate and organize these statistics. Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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Valued Member
 Canada
72 Posts |
I actually found my way to 31 USC 5113 before your post and as you say it's not at all nicely organized which wasn't surprising.
Does the mint actually keep [ongoing] statistics on the coins it produces through some sampling methodology? You would think they should to [continually] prove that they are compliant with the legislation. [Edited]
I wouldn't be surprised if things were less well controlled in earlier times. I would think coin making apparatus back then were not as precisely machined or tooled as equipment today.
I would think the precise tolerances for circulated coinage would be much harder to specify without alot of data which might be harder to collect. It would be interesting if the professional grading services kept statistics on coin weight/diameter as a function of date and grade compared to design targets.
Just some thinking on my part...... we have much more knowledgeable experts here.
Edited by lahave56
04/15/2026 4:53 pm
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Forum Dad
United States
24148 Posts |
Quote:
I would think the precise tolerances for circulated coinage would be much harder to specify without a lot of data which might be harder to collect. You're reading way too much into it. "Tolerances" are supposed to be what the mint says they are. But they really don't mean much. There are legitimate light and heavy coins due to rolled thin and thick stock, and blanks are sometimes punched from the tapered ends, too. "Precise" is a term I would never use referring to US Mint Weight Tolerances. They are guidelines at best. You can't say a coin is fake because it's outside the tolerances, so they are not precise. |
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Moderator
Australia
16808 Posts |
Technically, a coin isn't legal tender if it's weight is outside the tolerance limits. But the requirement for coins to be independently verified to ensure the Mint is complying with their own guidelines in terms of coin weight and composition has long lapsed. The Coinage Act of 1792 provided for freshly minted US coins to be randomly sampled and tested via the Assay Commission, in a system designed to emulate the British Trial of the Pyx. But with precious metals no longer being used in coinage, independent testing was deemed to be no longer needed. The Assay Commission last met to test coins in 1971 but they had no coins to test since by then everything was base-metal; the Assay Commission was formally abolished in 1980. The US government now trusts the US Mint's own internal quality control checks. Having quality control checks in place is better than having no quality control checks at all, but no system is perfect; "defective" coins will slip out. But ideally, not many of them. Mint errors are valuable because they're rare, and they're rare because the Mint's quality controls mean few of them are made and even fewer of them escape into the hands of the public. Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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Valued Member
Canada
72 Posts |
@bobby131313 and @Sap thanks for the comments. I was really just wondering where the values in the table came from. I figured they were based on some statistics from somewhere. I appreciate the history @Sap posted. I can see how weight would be of much more importance when considering coins with precious metals. I found the backstory on the British Trial of the Pyx to be quite interesting. I've been trying to learn a bit about Counterfeit Detection of coins and it seemed that weight and diameter are a couple of factors to consider among others. In terms of a coins actual measurements of diameter and weight and it's authenticity it seems to be a judgment call based on the design target, when the coin was made and it's condition. Thanks for the helpful comments. |
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Pillar of the Community
 United States
4588 Posts |
Lastly, you need to reference the legislation as well as common practices. For example, most tolerances are defined as 95%, which means as much as 5% of a sample could be higher or lower, and the batch is still considered within tolerance. For example... https://www.usmint.gov/learn/histor...april-2-1792Quote:
SEC. 9. And be it further enacted, That there shall be from time to time struck and coined at the said mint, coins of gold, silver, and copper, of the following denominations, values and descriptions, viz. Eagles—each to be of the value of ten dollars or units, and to contain two hundred fort-seven grains and four eighths of a grain of pure, or two hundred and seventy grains of standard gold. Quote:
SEC. 18. And the better to secure a due conformity of the said gold and silver coins to their respective standards, Be it further enacted, That from every separate mass of standard gold or silver, which shall be made into coins at the said Mint, there shall be taken, set apart by the Treasurer and reserved in his custody a certain number of pieces, not less than three, and that once in every year the pieces so set apart and reserved, shall be assayed under the inspection of the Chief Justice of the United States, the Secretary for the Department of State, and the Attorney General of the United States, (who are hereby required to attend for that purpose at the said Mint, on the last Monday in July in each year,) or under the inspection of any three of them, in such manner as they or a majority of them shall direct, and in the presence of the Director, assayer and chief coiner of the said Mint; and it shall be found that the gold and silver so assayed, shall not be inferior to their respective standards herein before declared more than one part in one hundred and forty-four parts, the officer or officers of the said Mint whom it may concern shall be held excusable; but if any greater inferiority shall appear, it shall be certified to the President of the United States, and the said officer or officers shall be deemed disqualified to hold their respective offices. If you think about it, this is saying that a lot of 3 coins can't be out of specifications by 1/144th (0.6944...%) out of the weight of two hundred forty-seven grains and four eighths of a grain of gold. Or 1.71875 grains per coin. -----Burton 50+ year / Life / Emeritus ANA member (joined 12/1/1973) Life member: Numismatics International, CONECA Member: TNA, FtWCC, NETCC, EveryCountry (online) coin club Owned by three cats and a wife of 40+ years (joined 1983) Author: 3rd Edition of the Sample Slabs book, https://www.sampleslabs.info/ |
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Valued Member
Canada
72 Posts |
Quote:
most tolerances are defined as 95% @Bstrauss3 I guess they weren't using 95% confidence intervals back in the early days  The system described though does seem quite similar to the system used by the British that was mentioned by @Sap - of course the players were a bit different - but perhaps comparable. I also find it interesting that the Secretary of the Treasury (estab. in 1789) was not involved in the assay oversight but the chief justice was. I also remember reading that when the mint was originally established in 1792 that they initially wanted the people responsible to put up a bond of like $10K but I think they relented to something less onerous when [there was pushback]. [See the history of the Flowing Hair silver dollar in this forum]. The history is pretty interesting. [Edited] Edited by lahave56
04/17/2026 1:56 pm
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Posted 04/14/2026 6:41 pm
