Methodology: How We Calculate Gold Prices
Every price on GoldRates Hub comes from two inputs: the international spot price of each metal and the exchange rate of each currency. This page explains where they come from, how often they update and how we combine them.
Data sources
- Metals: spot prices for gold (XAU), silver (XAG), platinum (XPT) and palladium (XPD) in US dollars per troy ounce come from Gold API, which aggregates quotes from the wholesale markets.
- Exchange rates: mid-market rates from ExchangeRate-API, with a public backup source if the main one does not respond.
- History: we record each day’s open, high, low and close (UTC) ourselves, starting from the day the site went live. The long-term chart on the history page is a TradingView chart (OANDA:XAUUSD) that only loads when you click.
Update frequency
Metal prices refresh about every 60 seconds and the page updates itself in your browser. Exchange rates refresh at most hourly, although the free source publishes new values once a day. The gold market is closed from Friday evening to Sunday evening New York time; during that window you will see Friday’s last price.
The formula
Local price per gram = spot price (USD per troy ounce) ÷ 31.1034768 × purity × exchange rate (currency per USD)
Worked example with live data: 4,129.30 USD ÷ 31.1034768 = 132.76 USD per gram of pure gold. For 18K (purity 0.750) in British pounds: 132.76 × 0.750 × 0.7423 = 73.91 GBP per gram.
Purity values
| Karat | Hallmark | Purity used |
|---|---|---|
| 24K | 999 | 1.000 |
| 23K | 958 | 0.958 |
| 22K | 916 | 0.916 |
| 21K | 875 | 0.875 |
| 20K | 833 | 0.833 |
| 19K | 792 | 0.792 |
| 18K | 750 | 0.750 |
| 16K | 667 | 0.667 |
| 15K | 625 | 0.625 |
| 14K | 585 | 0.585 |
| 12K | 500 | 0.500 |
| 10K | 417 | 0.417 |
| 9K | 375 | 0.375 |
| 8K | 333 | 0.333 |
| 6K | 250 | 0.250 |
24K is priced as pure gold (1.000); 999.9 and 999 bars differ by at most 0.1%. For 14K we use 0.585, the usual legal hallmark, rather than 14/24 = 0.583.
Weight units
Troy ounce = 31.1034768 g · tola = 11.6638 g · tael (Hong Kong) = 37.429 g · Thai baht = 15.244 g · chỉ and don = 3.75 g · sovereign/pavan = 8 g · mithqal (Islamic weight) = 4.25 g · pennyweight = 1.5552 g · grain = 0.0648 g · kilogram = 1,000 g.
Buy and sell prices
The buy (bid) and sell (ask) columns are estimates: we apply a ±2% margin to the spot value, which you can change on each page. A shop’s real margin depends on the country, the type of item and the quantity.
Daily change
The change is measured against the last recorded close of the previous day (UTC). Other sites use the New York close, so their percentages can differ slightly.
Limitations
- Prices exclude dealer margins, taxes, import duties and making charges.
- In countries with more than one exchange rate (for example Argentina, Venezuela, Lebanon or Nigeria) the real local price can differ a lot from a conversion at the official rate.
- Different providers show slightly different figures at the same moment; a gap of a few dollars per ounce is normal.
Corrections
If you spot a wrong figure, email contact@goldrateshub.com. We check every report and fix confirmed errors.