Definition and Weight Standard
A 1 oz gold bar contains exactly one troy ounce of refined gold. A troy ounce equals 31.1035 grams, which is slightly heavier than a standard ounce (28.35 grams). This measurement system has been used for precious metals trading for centuries.
Most 1 oz gold bars are refined to .9999 purity, meaning 99.99% pure gold. Some older or specialty bars may be .999 (99.9%) pure. The purity is typically stamped directly on the bar along with the weight.
Physical Characteristics
The dimensions of a 1 oz gold bar vary by manufacturer, but they typically measure around 50mm long, 28mm wide, and 1.5mm thick. The exact shape can be rectangular with rounded or squared corners depending on the refiner.
Each bar displays key information on its face: the weight (1 oz or 31.1g), purity (.9999), refiner name or logo, and often a unique serial number. The reverse may be plain or include additional security features.
How Bars Differ from Coins and Rounds
Gold bars are produced by private refiners and do not carry legal tender status. Gold coins, by contrast, are minted by government mints and have a face value (though the gold content far exceeds that value). Gold rounds look like coins but are privately minted without legal tender status.
Bars generally carry lower premiums than coins because they cost less to produce. Coins often have collectible appeal and recognizable designs that add to their premium over spot price.
Common Refiners
Several refiners produce widely recognized 1 oz gold bars. These include PAMP Suisse, Valcambi, Argor-Heraeus, Perth Mint, Royal Canadian Mint, and Credit Suisse (now produced by other refiners). Bars from LBMA-accredited refiners are generally accepted worldwide. Learn more about LBMA accreditation and why it matters.
Brand recognition can affect resale ease, but any bar from a reputable refiner should be sellable. Some buyers prefer specific brands for their security features or packaging, while others focus primarily on gold content and price. Understanding how gold bars are made can help you appreciate the quality differences between refiners.