Data sources and calculations

Where prices come from

Gold, silver and currency reference rates are supplied by MetalpriceAPI. We currently use its free plan, with 24-hour-delayed data for personal, non-commercial evaluation.

When prices update

The server attempts a refresh at most once every 24 hours when someone visits. The market timestamp describes the supplier’s data; the last successful check describes when this website retrieved it. A refresh does not guarantee a newer market timestamp.

If a refresh fails, previously saved data may be shown with a stale notice. Market data more than seven days old is rejected. When no usable feed is available, the calculator clearly labels its prices, exchange rates and charts as illustrative samples.

How the estimate is calculated

Estimated value = weight in grams × purity × reference price per gram.

One troy ounce is 31.1034768 grams. Currency conversion uses the supplier’s exchange rates. A 916 hallmark means 91.6% purity; 22K is calculated as 22 ÷ 24, approximately 91.67%. A 750 hallmark and 18K both mean 75%.

Charts and limitations

Invented demonstration charts are hidden when actual market data is connected. We do not currently provide historical market charts. Reference prices can differ from a dealer’s buying or selling price.