Troy Ounce Converter: Troy Ounces to Grams, Pennyweights, Grains and Kilograms

How it works

1 troy ounce (oz t) = 480 grains = 20 pennyweights = 31.1034768 g exactly · 1 grain = 64.79891 mg · 1 pennyweight (dwt) = 24 grains = 1.55517384 g · 1 troy pound = 12 oz t = 373.2417216 g · 1 avoirdupois ounce = 437.5 grains = 28.349523125 g · 1 kg = 32.1507 oz t · 1 tola = 3/8 oz t = 11.6638 g · result = amount × grams per “from” unit ÷ grams per “to” unit

Precious metals use the troy system, which shares one unit with everyday weights: the grain, fixed at exactly 64.79891 mg since 1959. A troy ounce is 480 grains (31.1035 g) and splits into 20 pennyweights of 24 grains each, the unit jewelers and scrap buyers use. An ordinary (avoirdupois) ounce is only 437.5 grains (28.35 g), so a troy ounce is about 9.7% heavier, but a troy pound has just 12 ounces and is lighter than a regular pound. The converter turns any amount into grams first and then into the unit you want, and lists the same weight in every unit, plus regional units such as the tola (South Asia and the Gulf) and the Hong Kong tael. Under More options, set the purity to see the pure metal in a karat-gold or sterling piece, and enter a spot price per troy ounce to value it. That is a quick melt value only; dealers buy below spot and sell above it. Use the grams-to-ounces food converter for kitchen ounces, and the gold and silver spot value calculator for detailed coin and bar pricing.

Worked example

Converting 1 troy ounce to grams: 1 × 31.1034768 g = 31.1035 g. The same ounce is 20 pennyweights, 480 grains, 0.0311035 kg, 1.09714 avoirdupois ounces, 0.0833333 troy pounds and 2.66667 tolas. A 1 kg bar is 1,000 ÷ 31.1034768 = 32.1507 troy ounces.

Sources: Wikipedia: Troy weight (grain, pennyweight, troy ounce and pound definitions) · NIST Office of Weights and Measures: Precious metals conversion information · Wikipedia: Tael (Hong Kong, Singapore, Taiwan and mainland values)

Frequently asked questions