Troy Ounces Converter
Convert between troy ounces and grams for precious metals like gold and silver. Enter values for instant results with step-by-step formulas.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator
Troy Ounces Converter
Calculator
Adjust values & calculateEnter your values below. Every result is computed in your browser — no data is sent to any server.
Formula: Grams = Troy Ounces x 31.1035
Worked example — 5 troy oz = 155.52 g = 5.49 avoirdupois oz | Value: $11,750
Formula
Grams = Troy Ounces x 31.1035
Where 1 troy ounce equals exactly 31.1034768 grams. A troy ounce is 9.7% heavier than a standard (avoirdupois) ounce of 28.3495 grams. For precious metals pricing: Value = Troy Ounces x Spot Price per Troy Ounce.
Worked Examples
Example 1: Gold Investment Value Calculation
Problem:Calculate the value of 5 troy ounces of gold at a spot price of $2,350 per troy ounce. Also convert to grams and avoirdupois ounces.
Solution:Weight in grams = 5 x 31.1035 = 155.52 g Weight in avoirdupois oz = 5 x 1.09714 = 5.49 oz Weight in pounds = 5.49 / 16 = 0.343 lb Gold value = 5 x $2,350 = $11,750 Pennyweights = 5 x 20 = 100 dwt Grains = 5 x 480 = 2,400 grains
Result:5 troy oz = 155.52 g = 5.49 avoirdupois oz | Value: $11,750
Example 2: Scrap Gold Weight Conversion
Problem:A jeweler has 85 grams of 14-karat scrap gold. Convert to troy ounces and calculate melt value at $2,350/oz.
Solution:Troy ounces = 85 / 31.1035 = 2.733 troy oz Pure gold content (14K) = 2.733 x (14/24) = 1.594 troy oz Melt value = 1.594 x $2,350 = $3,746 Pennyweights total = 2.733 x 20 = 54.66 dwt Pure gold pennyweights = 54.66 x 0.583 = 31.87 dwt
Result:85 g = 2.733 troy oz total | 1.594 troy oz pure gold = $3,746 melt value
Frequently Asked Questions
What is a troy ounce and how does it differ from a regular ounce?
A troy ounce is a unit of weight measurement used exclusively for precious metals such as gold, silver, platinum, and palladium. One troy ounce weighs exactly 31.1034768 grams, which is approximately 9.7 percent heavier than a standard avoirdupois ounce of 28.3495 grams. The troy system originated in the Middle Ages from the French trading city of Troyes, which hosted major international trade fairs. When gold is priced at a certain amount per ounce, it always refers to the troy ounce, not the standard ounce. This distinction is critically important because confusing the two units when buying or selling precious metals results in roughly a 10 percent pricing error that could mean thousands of dollars on large transactions.
Why are precious metals measured in troy ounces instead of regular ounces?
The use of troy ounces for precious metals is a historical convention dating back to medieval European trade that has persisted because of standardization and industry practice. The troy weight system was already established for precious metals trading at the Troyes fairs in France by the 12th century, and it was formally adopted into English law by Henry VIII in 1527. The troy system provides finer divisions that are useful for precious metals: one troy ounce contains 20 pennyweights, and one pennyweight contains 24 grains, giving exactly 480 grains per troy ounce. This system was embedded into international trade, banking, and commodity markets so deeply that changing to metric or avoirdupois would cause massive confusion. All major precious metals exchanges worldwide including COMEX, LBMA, and the Shanghai Gold Exchange quote prices per troy ounce.
How do I convert between troy ounces and grams for gold?
To convert troy ounces to grams, multiply by 31.1035. To convert grams to troy ounces, divide by 31.1035. For example, a standard 1 troy ounce gold coin like the American Gold Eagle weighs exactly 31.1035 grams. A 10-gram gold bar equals 0.3215 troy ounces. A 1-kilogram gold bar contains 32.1507 troy ounces. To calculate the value of gold in grams, divide the per-troy-ounce price by 31.1035. If gold costs $2,350 per troy ounce, the price per gram is $75.56. These conversions are essential when comparing gold products sold in different units or when purchasing gold in countries that price by the gram rather than the troy ounce.
What is a pennyweight and how does it relate to troy ounces?
A pennyweight, abbreviated dwt, is a traditional unit of weight in the troy system equal to one-twentieth of a troy ounce, or approximately 1.5552 grams. The name comes from the weight of a medieval English silver penny. Pennyweights are commonly used in the jewelry industry in the United States for pricing and weighing gold jewelry, dental gold, and scrap precious metals. When a jeweler or gold buyer quotes a price per pennyweight, multiply by 20 to get the equivalent price per troy ounce for comparison with spot prices. For example, if a gold buyer offers $100 per pennyweight, that equals $2,000 per troy ounce. Jewelers also use the grain, where 24 grains equal one pennyweight and 480 grains equal one troy ounce.
How do international gold markets use troy ounces?
Major international gold markets universally use the troy ounce as their standard unit of trade, though some regional markets also quote in grams or kilograms. The London Bullion Market Association (LBMA) sets the global gold price benchmark twice daily in US dollars per troy ounce. The COMEX division of the New York Mercantile Exchange trades gold futures contracts based on 100 troy ounces per contract. The London Good Delivery bar, the standard for international settlement, weighs approximately 400 troy ounces (12.4 kg). The Shanghai Gold Exchange quotes prices in Chinese yuan per gram but converts to troy ounce equivalents for international comparison. Indian gold markets often price in rupees per 10 grams. Despite these regional variations, the troy ounce remains the universal reference point for comparing gold prices worldwide.
What are the standard sizes of gold and silver bullion products?
Gold and silver bullion comes in standardized sizes that are all measured in troy ounces or metric grams. Common gold bullion coins include 1 troy ounce (31.1 g), 1/2 ounce (15.55 g), 1/4 ounce (7.78 g), and 1/10 ounce (3.11 g). Gold bars range from 1 gram to the 400 troy ounce London Good Delivery bar. The most popular gold bar sizes for retail investors are 1 ounce, 10 ounce, and 1 kilogram (32.15 troy ounces). Silver bullion is also denominated in troy ounces, with common products being 1 ounce rounds and coins, 10 ounce bars, 100 ounce bars, and 1,000 ounce industrial bars used for COMEX delivery. The premiums over spot price generally decrease as bar size increases because manufacturing and packaging costs are spread over more metal.
How does the troy system affect gold jewelry pricing?
Gold jewelry pricing involves troy weight but adds complexity because jewelry is rarely pure gold. The karat system indicates purity: 24 karat is pure gold, 18 karat is 75 percent gold, 14 karat is 58.3 percent gold, and 10 karat is 41.7 percent gold. To calculate the gold content value of a piece of jewelry, first weigh it in troy ounces or grams, then multiply by the karat purity fraction, then multiply by the current spot gold price. For example, a 14-karat necklace weighing 1 troy ounce contains 0.583 troy ounces of pure gold. At $2,350 per troy ounce, the gold content value is approximately $1,370. The retail price of jewelry typically exceeds the gold value by two to five times due to design, craftsmanship, brand markup, and retail overhead.
What is the difference between a troy pound and an avoirdupois pound?
The troy pound and avoirdupois pound differ in both total weight and subdivision, creating a confusing asymmetry. A troy pound contains 12 troy ounces and weighs 373.24 grams, while an avoirdupois pound contains 16 avoirdupois ounces and weighs 453.59 grams. This means a troy pound is actually lighter than an avoirdupois pound, even though a troy ounce is heavier than an avoirdupois ounce. The troy pound is rarely used in practice because the precious metals industry works primarily in troy ounces and the troy pound was officially abolished in the UK in 1878. Understanding this distinction prevents expensive calculation errors when working with larger quantities of precious metals, particularly when converting between troy ounces and avoirdupois pounds for shipping or inventory purposes.
How do I verify if a gold bar or coin weighs the correct troy ounce amount?
Verifying precious metals weight requires a precision scale calibrated in grams or troy ounces with at least 0.1 gram resolution for coins and 0.01 gram for smaller pieces. A genuine 1 troy ounce gold coin should weigh 31.103 grams (with minor tolerance of plus or minus 0.05 grams for government coins). The total weight of a gold coin may exceed the gold content weight because some coins contain alloy metals for durability. The American Gold Eagle, for instance, weighs 33.93 grams total but contains exactly 1 troy ounce (31.103 g) of pure gold with the remaining weight being copper and silver alloy. The Canadian Gold Maple Leaf is 99.99 percent pure and weighs 31.103 grams total. Always compare your measurement against the published specifications for the specific product and be suspicious of items that are more than 0.5 percent off the expected weight.
What other precious metals use the troy ounce system?
All major precious metals are traded and priced using troy ounces including gold, silver, platinum, and palladium. Silver is the most widely traded precious metal by volume, with prices quoted per troy ounce and industrial bars weighing 1,000 troy ounces used for exchange delivery. Platinum group metals including platinum, palladium, rhodium, ruthenium, iridium, and osmium all use troy ounce pricing. Platinum typically trades between $800 and $1,200 per troy ounce, while palladium has ranged from $500 to $3,000 per troy ounce depending on automotive catalyst demand. Rhodium is the most volatile, having traded between $2,000 and $29,000 per troy ounce in recent years. The troy ounce standard ensures consistent pricing across all precious metals markets worldwide, making it easier for investors and industrial buyers to compare relative values.
References
Reviewed for accuracy by Manoj Kumar, Mathematics Educator · Editorial policy
Related Calculators
🧮Ounces to Grams Converter
Convert weight between ounces, grams, pounds, and milligrams.
🧮Dry Ounces to Cups Converter
Convert dry ounces to cups for flour, sugar, and other baking ingredients.
🧮Grams to Ounces Cooking Converter
Convert ingredient weights between grams and ounces for international recipes.
🧮Pounds to Kilograms Converter
Convert weight between pounds, kilograms, stones, and ounces with precision.
🧮Gallons to Liters Converter
Convert between gallons (US/Imperial), liters, quarts, and fluid ounces.
🧮Sticks of Butter to Cups Converter
Convert butter sticks to cups, tablespoons, grams, and ounces for baking.