Why USD Here Is Derived, Not a Native Feed
This site's live gold price does not come from a US-dollar spot feed directly. It reads the already-published gold price from our sister site, Gold Price Per Gram UK (in turn sourced from goldapi.io, GBP), and converts it to USD using a live GBP→USD exchange rate from frankfurter.dev (European Central Bank reference rates, no API key required). We disclose this rather than presenting the USD figure as if it came from a native dollar feed — it's a two-step calculation, and the accuracy of the USD price depends on both the UK site's gold price and the FX rate being current.
Update Frequency
The gold spot price refreshes three times per day. The GBP→USD rate is sourced from the ECB, which publishes new reference rates once per working day (around 16:00 CET) — so on a typical day, our 3x/day polling of the FX rate mostly re-reads the same daily figure, while the gold spot price itself still updates three times. Every page shows the exact "Last refreshed" timestamp of the price data currently displayed. If either upstream source is temporarily unavailable, the site falls back to the last known value for that component specifically and shows a clear "using cached rate" banner, rather than a broken or zeroed page.
Calculation Formula
The formula actually used depends on the karat — most karats are read directly from the UK site's own per-karat quote (which itself ultimately comes from goldapi.io's own per-karat pricing, not a simple fraction of the 24K rate), rather than being derived locally:
price_per_gram(karat, GBP) = UK_site.pricePerGram[karat]
price_per_gram(karat, USD) = price_per_gram(karat, GBP) × GBP_to_USD_rate
// 10K has no UK equivalent purity, so it's the one karat actually derived by fraction
price_per_gram(10k, GBP) = UK_site.pricePerGram['24k'] × 0.417
price_per_gram(10k, USD) = price_per_gram(10k, GBP) × GBP_to_USD_rate
cash_estimate(karat, USD) = price_per_gram(karat, USD) × buyer_discount_factor
The "fine gold fraction" table below is accurate as a reference (it's the standard fineness for each karat), but it is not the formula actually applied for 24K/22K/18K/14K — those come straight from the UK site's own per-karat feed, which can differ very slightly (typically well under 0.5%) from a naive 24K × fraction calculation, since goldapi.io quotes each karat independently rather than deriving it from a fixed fraction.
Karat Fractions — Reference & Fallback Values
| Karat | Stamp | Fine gold fraction | Price source |
|---|---|---|---|
| 24K | 24K | 1 | UK site's own per-karat quote (direct) |
| 22K | 22K | 0.9167 | UK site's own per-karat quote (direct) |
| 18K | 18K | 0.75 | UK site's own per-karat quote (direct) |
| 14K | 14K | 0.585 | UK site's own per-karat quote (direct) |
| 10K | 10K | 0.417 | Derived: 24K × fraction (fallback, no UK equivalent) |
Cash-for-Gold Discount
The cash-for-gold estimate applies a configurable discount factor (currently 0.85) to the live per-gram USD price. This is explicitly an estimate, not a market rule — real pawn shop and gold-buyer offers vary by karat, weight sold and the individual buyer. Always get a real quote before selling.
Value-by-Weight Tables
The "value by weight" tables shown on the homepage, each karat page and each city page use the exact same per-gram price as the main calculator above them — they simply multiply it by a fixed set of common weights, so they refresh from the same live data with no separate calculation:
value(1 troy oz) = price_per_gram(karat, USD) × 31.1035
Coin Melt Value Formula (AGW)
The coin melt value calculator prices each coin by its Actual Gold Weight (AGW) — the pure-gold content in troy ounces, a fixed mint specification independent of the coin's total weight or face value — at the live 24K (pure gold) rate. Coin AGW figures are standard published mint specs, not derived from the karat-fraction table above:
melt_value(qty) = melt_value(coin, USD) × quantity
Melt value is a floor, not a resale estimate — it excludes any numismatic/collector premium. See the coin page for AGW figures used for each listed coin.
Who Runs This Site
Gold Price Per Gram USA is an independent calculator site, and the US-market companion to Gold Price Per Gram UK. It is not a dealer, refiner or financial adviser, and prices shown are indicative only — always confirm with a buyer or jeweler before any transaction.