Where every number on CurioFeed comes from

Print runs and star notes

The star note lookup does not calculate anything. It reads a database we built from the monthly production reports of the Bureau of Engraving and Printing — 284 reports covering October 2002 to May 2026, parsed into 684 rows and deduplicated to the 678 print runs published here — four exact duplicates and two unreadable rows were removed.

• Source: BEP monthly production reports, published by the US Department of the Treasury.
• License: works of the US federal government are in the public domain under 17 U.S.C. §105.
• How it is checked: after every rebuild, the packed dataset is queried run by run against the original database and must return exactly the same rows. A packer that quietly loses rows is worse than no packer at all.
• How often it changes: the BEP publishes roughly one report a month. The dataset is refreshed from the new report; the coverage dates shown inside the tool tell you where it currently ends.

What the lookup deliberately does not do: tell you what your note is worth in dollars. We know how many notes were printed in that run. We do not know the condition of the one in your hand, and condition is most of the price. Anyone who quotes you a dollar figure from a serial number alone is guessing.

Coin weights and purities

The metal content of US coins is not a matter of opinion or of what a dealer’s chart says — it is written in statute. Every figure in the coin calculator is taken from the law itself:

• Coinage Act of 1873 — the .900 fine standard and the coin weights, given in grains.
• Coinage Act of 1965 (PL 89-81, 79 Stat. 254) — the 40 % silver Kennedy half.
• 31 U.S.C. §5112 — the modern bullion coins: Silver Eagle, Gold Eagle, Gold Buffalo.

Where the statute gives a weight in grains, we convert with the exact definitions below rather than repeating a rounded figure from somewhere else.

Units

Three definitions do all the work on this site, and all three are exact, not approximate:

• 1 troy ounce = 31.1034768 g, exactly. The troy pound has been defined in terms of the kilogram since 1959.
• 1 pennyweight = 1/20 troy ounce = 1.55517384 g, exactly. Tables that use 1.555 g lose about 11 mg per pennyweight.
• 1 grain = 1/480 troy ounce = 0.06479891 g, exactly.

Karat purity is a different kind of number. We use the hallmark standard, not the arithmetic fraction: 14K is 14 parts in 24, which is 583.3 fine, but pieces are made to 585 so they pass assay, and 585 is what a buyer pays against. The difference is 0.3 %. What is not defensible is printing “585” and calculating 583.

Metal prices

This is the only number on the site that moves, and it is the one we are most careful with. The worst thing this site could do is show you a frozen price as if it were today’s.

• Source: goldapi.io, quoted in US dollars per troy ounce.
• Cross-check: every quote is compared against a second, independent feed. If the two disagree by more than 1 % we flag it; by more than 3 %, we stop publishing a price at all.
• Staleness: the age of a quote is measured in open-market minutes. A Friday close read on a Sunday is not stale — the market is simply shut. A quote older than one full trading day is refused.
• Frozen-feed guard: if the price, or the source’s own timestamp, does not move between two readings separated by hours of open market, the feed is treated as broken even though it is answering normally. A “200 OK” is not a fresh number: that failure is exactly why one otherwise reputable data source was rejected for this site.
• Sanity bands: a quote outside a wide plausible range, or a gold-to-silver ratio outside historical bounds, is refused. This catches a price returned in the wrong unit or the wrong currency.

When any of those guards trips, the calculators do not show a number. They say the price is temporarily unavailable and why. An honest gap is worth more than an invented figure.

The price you see is a delayed market indication, not a dealer quote and not an offer. Nobody buys or sells at spot: a refiner or a scrap buyer keeps a margin, and that margin varies a lot.

What we do not do

• We do not buy or sell coins, notes, jewelry or metal, and we do not appraise anything.
• Nobody pays us to send you to a particular buyer.
• The calculators run entirely in your browser. What you type — weights, purities, how many coins you own — is never sent to us or to anyone else, and your browser never contacts the price provider directly.
• We do not use Google Analytics or any other audience measurement tool.

The site is funded by advertising. That is the whole business model, and it is why we can afford to tell you when we do not know something.

Corrections

If a figure here is wrong, we want to know — especially if you can point to the statute or the report that says so. Write through the contact form. Read the full disclaimer for what this site is and is not.