Data sources and calculations

Where prices come from

Gold, silver and currency reference rates are supplied by MetalpriceAPI. The supplier's data updates on a 30-minute schedule under our current plan.

When prices update

A scheduled server job checks hourly, and a visit can also trigger an eligible refresh. The request guard permits at most one supplier request per hour. 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, prices and estimates are hidden.

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%. See the gold purity guide.

Charts and limitations

Charts use recorded supplier prices and the exchange rate stored with each point. Collection began with this site's history feature, without invented historical backfill; a chart appears after two distinct updates. Up to 30 days of points are retained. Reference prices can differ from a dealer's buying or selling price.