What is the standard size of a bar of gold?

Most gold bars weigh between 1 troy ounce and 400 ounces, with the occasional exception being made for larger bars. The standard size of a bar of gold is therefore usually between 28 grams and 12.8 kilograms. The most popularly traded gold bars are those that weigh 1 troy ounce, with 100-troy-ounce bars also being fairly common. Smaller 1-gram and 5-gram gold bars are also available from some dealers, but these are generally more expensive on a per-gram basis than larger bars.