--- title: "Troy Ounce vs Gram: Understanding Bullion Weights" source: "https://goldealers.co.uk/knowledge/bullion/troy-ounce-vs-gram" date: "2025-12-02" --- # Troy Ounce vs Gram: Understanding Bullion Weights Precious metals are often quoted in troy ounces, which can confuse new sellers accustomed to grams or regular ounces. This article clarifies the difference between a troy ounce and other weight measures, since understanding these units is vital for calculating the value of coins, bars, and jewellery. At Goldealers, our quotes reference both grams and troy ounces to ensure complete clarity. ## What Is a Troy Ounce? A **troy ounce** (abbreviated as "ozt" or "oz t") is a unit of weight specifically used for precious metals: - **1 troy ounce = 31.1035 grams** - Used internationally for gold, silver, platinum, and palladium - The standard for pricing and trading precious metals ### Historical Origins The troy ounce dates back to medieval trading in Troyes, France, where merchants used this system for precious metals and gemstones. Despite its age, the troy ounce remains the global standard because financial markets and refineries worldwide have adopted it. ## Troy Ounce vs Avoirdupois Ounce This is where confusion often arises: ### Avoirdupois Ounce (Regular Ounce) - **1 avoirdupois ounce = 28.35 grams** - Used for everyday items (food, groceries, body weight) - What kitchen scales typically measure ### Troy Ounce - **1 troy ounce = 31.1035 grams** - Used exclusively for precious metals - About **10% heavier** than a regular ounce > This distinction is crucial: If you weigh your gold coin on a kitchen scale showing "1.1 oz," that's likely 1.1 avoirdupois ounces (about 31.2g), which equals roughly 1.003 troy ounces. Don't confuse the two when calculating value! ## Troy Ounce vs Gram For practical selling purposes, understanding the relationship between troy ounces and grams is essential: ### Conversion Formula - **1 troy ounce = 31.1035 grams** - **1 gram = 0.032151 troy ounces** ### Quick Reference Table | Troy Ounces | Grams | |-------------|-------| | 0.1 ozt | 3.11g | | 0.25 ozt | 7.78g | | 0.5 ozt | 15.55g | | 1 ozt | 31.10g | | 2 ozt | 62.21g | | 5 ozt | 155.52g | | 10 ozt | 311.03g | | 32.15 ozt | 1,000g (1kg) | ### Practical Examples **Example 1: Gold Price Conversion** If gold is quoted at £1,500 per troy ounce: - Per gram = £1,500 ÷ 31.1035 = **£48.23/gram** **Example 2: Jewellery Weight** You have 20 grams of 18 carat gold: - 18ct = 75% pure gold = 15g pure gold - 15g ÷ 31.1035 = **0.482 troy ounces** of pure gold - If gold is £1,500/ozt: 0.482 * £1,500 = **£723 gold content value** ## Why Troy Ounces Matter for Bullion Understanding troy ounces is particularly important when dealing with investment products: ### Bullion Coins Many popular bullion coins are denominated in troy ounces: - **1 oz Gold Britannia**: 31.1035g of 24 carat gold - **1 oz Gold Krugerrand**: 31.1035g of pure gold (total weight 33.93g at 22 carat) - **Gold Sovereign**: Actually 0.2354 ozt (7.32g at 22 carat) > Some coins like Krugerrands contain exactly 1 troy ounce of **pure gold** but weigh more than 31.1g total because they're alloyed with other metals for durability. The pure gold content is what matters for value. ### Bullion Bars Investment bars commonly come in these sizes: | Size | Weight (grams) | Troy Ounces | |------|---------------|-------------| | Small bar | 1g | 0.032 ozt | | Small bar | 5g | 0.161 ozt | | Small bar | 10g | 0.321 ozt | | Standard | 20g | 0.643 ozt | | Standard | 50g | 1.607 ozt | | Standard | 100g | 3.215 ozt | | Large | 250g | 8.038 ozt | | Kilobar | 1,000g | 32.151 ozt | ## How Dealers Quote Prices Different dealers may quote prices differently: ### Per Troy Ounce Quoting **Common in**: Financial markets, coin dealers, international trade **Example**: "Gold is trading at £1,500 per troy ounce today" **Advantage**: Easy to compare with international spot prices **Disadvantage**: Requires conversion for small items weighed in grams ### Per Gram Quoting **Common in**: Jewellery buyers, scrap gold dealers, everyday transactions **Example**: "We're paying £48.23 per gram for 24 carat gold" **Advantage**: Directly applicable to jewellery and small items **Disadvantage**: Harder to compare with international market prices ### Goldealers' Approach At Goldealers, we can work with either unit depending on what you're selling: - **Bullion coins/bars**: Often discussed in troy ounces - **Jewellery and scrap**: Usually calculated in grams - **Online quotes**: Our calculators handle both units automatically We ensure you understand exactly how we've calculated our offer, regardless of which unit we use. ## Converting Market Prices When you see gold prices in the news, they're typically quoted per troy ounce. Here's how to convert that to per-gram pricing: ### Conversion Example **Market price**: £1,500 per troy ounce **Step 1**: Divide by 31.1035 £1,500 ÷ 31.1035 = £48.23 per gram **Step 2**: Adjust for purity if needed - 24ct (100%): £48.23/gram - 18ct (75%): £48.23 * 0.75 = £36.17/gram - 9ct (37.5%): £48.23 * 0.375 = £18.09/gram **Step 3**: Apply dealer margin If a dealer pays 95% of spot for scrap: - 9ct offer: £18.09 * 0.95 = **£17.19/gram** > Goldealers often displays both the spot price and our offer percentage, making it easy to see you're getting a fair market rate without needing to do complex calculations. ## Other Precious Metal Weight Units While less common, you might encounter these: ### Pennyweight (dwt) - **1 pennyweight = 1.555 grams** - **20 pennyweights = 1 troy ounce** - Sometimes used in the US jewellery trade - Rarely seen in the UK ### Grain - **1 grain = 0.0648 grams** (approximately 65 milligrams) - **480 grains = 1 troy ounce** - Occasionally used for very small weights (gemstones, dental gold) - Historical unit, rarely relevant today ### Tola - **1 tola = 11.66 grams** (approximately 0.375 troy ounces) - Common in India and Middle Eastern gold markets - If you have jewellery marked in tolas, multiply by 11.66 to get grams ## Practical Tips for Sellers ### Use the Right Scale When weighing your precious metals at home: **For Grams**: Use a digital jewellery scale or kitchen scale with gram precision **For Troy Ounces**: Use a scale specifically designed for precious metals, or weigh in grams and convert **Avoid**: Kitchen scales that only show avoirdupois ounces – these will give incorrect values for precious metals > A standard bathroom or kitchen scale showing "ounces" is measuring avoirdupois ounces, not troy ounces. For accurate gold values, always work in grams and convert to troy ounces if needed. ### Double-Check Your Calculations Common pitfalls when doing calculations: ❌ **Wrong**: Treating regular ounces as troy ounces ❌ **Wrong**: Forgetting to account for purity (thinking 9ct gold weighs the same as pure gold per gram value) ❌ **Wrong**: Using rounded numbers (31g instead of 31.1035g for a troy ounce) ✓ **Right**: Using 31.1035 for conversions ✓ **Right**: Calculating pure gold content first (weight * purity) ✓ **Right**: Comparing dealer offers on the same unit basis ### Using Online Calculators Most precious metals dealers, including Goldealers, provide online calculators that handle conversions automatically: - Enter weight in grams or troy ounces - Select purity (carat for gold, sterling for silver, etc.) - Get instant estimated value This eliminates conversion errors and gives you a reliable baseline quote. ## Why Understanding Units Matters Knowing these weight conversions helps you: 1. **Verify Dealer Quotes**: Ensure you're getting fair value based on market prices 2. **Compare Offers**: Different dealers may quote in different units 3. **Avoid Confusion**: Don't accidentally underprice or overestimate your items 4. **Understand Market News**: Follow gold price movements and know how they affect your holdings ## Common Questions **Q: If I have 100 grams of 18ct gold, how many troy ounces of pure gold is that?** A: 100g of 18ct = 75g pure gold (18ct is 75% pure) 75g ÷ 31.1035 = **2.41 troy ounces** of pure gold **Q: Why don't dealers just use grams for everything?** A: International precious metal markets and prices are quoted in troy ounces because it's the global standard. However, many UK dealers (like Goldealers) work primarily in grams for customer convenience. **Q: Do I need to convert weights before getting a quote?** A: Not at Goldealers – we can handle any unit. Just tell us what you have (grams, troy ounces, or even avoirdupois ounces), and we'll calculate the value accurately. **Q: Are silver and platinum also measured in troy ounces?** A: Yes! Silver, platinum, palladium, and gold are all traded in troy ounces. The same conversion applies: 1 ozt = 31.1035g for all precious metals. ## Quick Reference Summary **Key Conversions to Remember:** - 1 troy ounce = 31.1035 grams - 1 gram = 0.032151 troy ounces - 1 troy ounce ≠ 1 regular ounce (it's about 10% heavier) - Most bullion coins are 1 troy ounce of pure gold - Jewellery is usually weighed in grams in the UK **When You See Prices:** - **"Per ounce" or "per ozt"**: That's a troy ounce (31.1035g) - **"Per gram"**: Direct weight unit (no conversion needed) - **On a kitchen scale**: Likely avoirdupois ounces (28.35g) – convert to grams first ## Final Thoughts Understanding troy ounces versus grams isn't just academic – it directly affects how much money you receive when selling precious metals. While the conversions might seem complex at first, they become intuitive with practice. At Goldealers, we make the process straightforward by providing clear quotes in the unit that makes sense for your items, with full transparency about how we calculate values. Whether you're selling a single coin measured in troy ounces or a bag of jewellery weighed in grams, we ensure you understand the conversion and receive a fair price based on the current market. > When in doubt, always ask your dealer to explain their calculations. A reputable dealer like Goldealers will be happy to show you exactly how they arrived at their offer, including any unit conversions. --- **Need help calculating your precious metals value?** Use Goldealers' online calculator or [contact us](/contact) for a clear, transparent quote in any unit you prefer. --- *Published by Goldealers Ltd · https://goldealers.co.uk/knowledge/bullion/troy-ounce-vs-gram*