Unit Converter — Convert Troy Ounces, Grams and Kilograms
31.1035g Gold
3,893.95 €
Spot price: 125.1934 €/g
| Unit | = Grams | = Troy Ounces |
|---|---|---|
| 1 Troy Ounce (troy oz) | 31.1035 | 1.0000 |
| 1 Gram | 1.0000 | 0.03215 |
| 1 Kilogram | 1,000.0000 | 32.1507 |
| 1 Pennyweight | 1.5552 | 0.05000 |
| 1 Grain | 0.06479891 | 0.00208 |
| 1 Tola | 11.6638 | 0.37500 |
| 1 Tael (Chinese) | 37.4290 | 1.2034 |
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The Troy Ounce — International Standard Unit
Anyone dealing with precious metal prices for the first time will immediately encounter the term troy ounce (abbreviation oz t or simply oz). One troy ounce equals exactly 31.1034768 grams — an unusual weight at first glance, with roots in medieval France.
Where does the name come from?
The name derives from the French trading city of Troyes in the Champagne region. In the 12th and 13th centuries, the most important trade fairs in Europe were held there. Merchants from all over Europe needed a uniform weight system to trade precious metals, spices and other goods fairly. The pound and ounce system used in Troyes prevailed and became the standard for precious metals — a standard that remains unchanged to this day.
Troy ounce vs. regular ounce
The troy ounce must not be confused with the regular ounce (avoirdupois ounce), which is used in the Anglo-Saxon world for everyday goods such as food or parcels. The avoirdupois ounce weighs only 28.3495 grams — approximately 10 % less than the troy ounce. Anyone who accidentally calculates with the wrong unit will quickly make an error of several hundred euros with gold.
Why exactly 31.1035 grams? The Troy pound was fixed at exactly 5,760 grains in the British Weights and Measures Act of 1824. One grain equals 0.06479891 grams (derived from the weight of a barleycorn). One troy ounce comprises 480 grains: 480 × 0.06479891 = 31.1034768 grams. This value was internationally standardized in 1959 and is today identical in every precious metal market worldwide.
Precious Metal Units Worldwide
Although the troy ounce is the international standard, different regions of the world traditionally use their own weight units for precious metals. Anyone comparing prices internationally or wanting to trade in a specific market should know these units.
- ◆ Troy Ounce — 31.1035 g: The globally valid unit of measurement at all major exchanges (LBMA London, COMEX New York, SGE Shanghai). Every internationally quoted precious metal price refers to this unit.
- ◆ Gram / Kilogram — metric system: In Europe, Australia and many other countries, private investors prefer the metric designation. Bars are frequently offered in grams (1 g, 5 g, 10 g, 50 g, 100 g) or kilograms. One kilogram equals 32.1507 troy ounces.
- ◆ Tael (Liang) — 37.429 g: The traditional weight unit in China, Hong Kong and Taiwan. Gold trading at the Chinese Gold and Silver Exchange Society in Hong Kong is quoted in tael. There are regional variations: in mainland China 1 tael = 50 grams, while in Hong Kong and Taiwan it is 37.429 g (based on the traditional system).
- ◆ Tola — 11.6638 g: In India, Pakistan, Bangladesh and parts of the Middle East, the tola is the common unit for gold purchases. Its origin lies in the Indian coinage of the Mughal era. Gold jewelry in India is almost exclusively weighed and traded in tola. Ten tola equal one "bhari" and are frequently offered as standard bars.
- ◆ Pennyweight (dwt) — 1.5552 g: Primarily used by jewelers in the USA and Great Britain. One pennyweight equals 1/20 of a troy ounce. The name originates from the weight of an English silver penny in the Middle Ages. In the jewelry industry, this unit remains the standard for price calculation.
- ◆ Grain — 0.0648 g: The oldest weight unit still in use, originally defined as the weight of a barleycorn. Today mainly used in pharmacy and ammunition manufacturing. In precious metal trading, the grain is the base unit from which the troy ounce is derived: 1 oz = 480 grains.
Practical tip: When comparing international gold prices, always pay attention to the unit. A gold price of "2,200" can mean 2,200 USD per troy ounce, 2,200 HKD per tael or 2,200 INR per tola — completely different amounts. Our converter above automatically converts between all common units.
From Ounce Price to Gram Price
The gold price is quoted on exchanges in US dollars per troy ounce. For European investors who think in grams and euros, two conversion steps are needed: the weight conversion and the currency conversion. Here is a concrete calculation example:
Step-by-Step Conversion
Why the gram price matters more for European buyers
In continental Europe, bars and coins are almost always offered in grams or kilograms. When you want to buy a 10-gram gold bar online, you compare the price with the calculated material value (10 × EUR gram price). The difference to the actual selling price is the so-called premium, which covers manufacturing, distribution and trading costs.
The Exchange Rate Effect
The EUR/USD exchange rate has a significant impact on the euro gold price. When the euro falls against the dollar, the gold price in euros rises — even with an unchanged USD price. Conversely, a strong euro dampens the euro gold price. In practice, this currency effect can amount to 5 to 10 percentage points per year. European investors therefore benefit doubly when gold rises in USD while the euro weakens simultaneously.
Typical Trade Sizes for Precious Metals
Precious metals are traded in a wide variety of formats — from the 1-gram bar to the 400-ounce bank bar. The right size depends on the investment budget and the intended purpose.
Good Delivery Bars (Institutional Trading)
The Good Delivery bar is the standard in professional precious metal trading and is traded at the London Bullion Market Association (LBMA). For gold, it nominally weighs 400 troy ounces (approx. 12.44 kg); in practice, the permissible weight ranges between 350 and 430 oz. For silver, the standard weight is 1,000 troy ounces (approx. 31.1 kg). These bars are used by central banks, ETFs and wholesalers, and are generally not directly accessible to private investors.
Kilo Bars and Investment Bars
The 1-kilogram gold bar (32.15 oz) is the most popular bar in the upper-end retail segment and is also traded at the Shanghai Gold Exchange as a standard contract. Below that, there are bars in sizes of 500 g, 250 g and 100 g. The larger the bar, the lower the relative premium — because manufacturing and distribution costs are spread over more material.
Bullion Coins (1 oz)
The most popular denomination for private investors is the 1-ounce coin (31.1 g). Classics include the Krugerrand (South Africa), the Maple Leaf (Canada), the Vienna Philharmonic (Austria) and the American Eagle (USA). Bullion coins have the advantage of being globally recognized, easily tradable and available in small denominations (1/2 oz, 1/4 oz, 1/10 oz). The premium for 1-oz coins is typically 3–6 %.
Gram Bars for Beginners
For investors with a smaller budget, LBMA-certified manufacturers such as Heraeus, Umicore, Valcambi or PAMP offer bars from 1 gram. Common sizes are 1 g, 5 g, 10 g, 20 g, 50 g and 100 g. The downside: the relative premium increases significantly for smaller bars.
Typical Premium by Bar Size (Gold)
| Size | Weight | Premium (approx.) |
|---|---|---|
| 1 g Bar | 1.00 g | 8–15% |
| 5 g Bar | 5.00 g | 5–8% |
| 10 g Bar | 10.00 g | 4–6% |
| 1 oz Coin | 31.10 g | 3–6% |
| 50 g Bar | 50.00 g | 2.5–4% |
| 100 g Bar | 100.00 g | 1.5–3% |
| 250 g Bar | 250.00 g | 1–2% |
| 1 kg Bar | 1,000.00 g | 0.8–1.5% |
Rule of thumb: The smaller the denomination, the higher the premium — but also the more flexible for a later partial sale. Many investors opt for a mix: a core of 100 g bars or 1 oz coins, supplemented by smaller units for liquidity.