Why Weight Units Trip People Up
Gold is traded, quoted, and priced in at least six different weight units around the world, depending on the market. A trader in New York looks at troy ounces. A jeweler in Mumbai talks about tolas. A merchant in Shanghai works in grams. A buyer in Dhaka thinks in bhoris. These are all real units in current use, and they are not the same as the ounces and grams that most people encounter in kitchens and grocery stores.
Getting the conversions right is not optional if you want to compare prices across markets, or compare a headline gold price to what your local jeweler is quoting. This piece walks through the units, the conversion factors, and the specific traps that trip people up.
The Six Units That Actually Matter
📊 Weight units for gold, with exact conversions
- Troy ounce (troy oz, ozt): The international benchmark unit. 1 troy oz = 31.1034768 grams.
- Gram (g): The metric standard. Used in Chinese, European wholesale, and increasingly Indian markets.
- Kilogram (kg): 1000 grams. Used for large bars and industrial contracts. 1 kg = 32.1507466 troy oz.
- Tola (Indian subcontinent): 1 tola = 11.66381 grams. Traditional unit still used at Indian, Pakistani, and Nepalese jewelry retail.
- Bhori (Bangladesh, sometimes vori): 1 bhori = 11.664 grams. Effectively the same as a tola in practice; historical fractional differences are within rounding.
- Baht (Thailand): 1 baht of gold = 15.244 grams (for jewelry) or 15.16 grams (for bullion, per Thai Gold Traders Association standard).
The ordinary avoirdupois ounce that appears on grocery labels is NOT the same as the troy ounce. 1 avoirdupois ounce = 28.3495 grams, versus 31.1035 grams for a troy ounce. A trader who confuses the two will get a systematic error of roughly 10% — enough to blow up a real transaction.
Working Through Common Conversions
Troy ounce to gram
1 troy oz = 31.1034768 g exactly. To convert an ounce price to a gram price: divide by 31.1035.
Example: COMEX gold at $4,000/oz. Price per gram = 4,000 ÷ 31.1035 = $128.60/g.
Gram to tola
1 tola = 11.66381 g. To convert per-gram to per-tola: multiply by 11.66381.
Example: Gold at $128.60/g. Price per tola = 128.60 × 11.66381 = $1,500.09/tola.
Troy ounce direct to tola
1 troy oz = 31.1035 g = 31.1035 / 11.66381 = 2.66667 tolas (approximately 2.6667). To go directly: divide by 2.6667.
Example: Gold at $4,000/oz. Price per tola = 4,000 ÷ 2.66667 = $1,499.99/tola.
MCX-style conversion (INR/10g to USD/oz)
MCX quotes in INR per 10 grams. To convert to USD per troy ounce:
Example: MCX gold quoted at 62,000 INR/10g, USD/INR = 83.5. Convert: (62,000 / 10) × 31.1035 / 83.5 = 6,200 × 31.1035 / 83.5 = $2,310/oz-equivalent.
SGE-style conversion (CNY/g to USD/oz)
SGE Au9999 quotes in CNY per gram. To convert:
Example: SGE at 570 CNY/g, USD/CNY = 7.2. Convert: 570 × 31.1035 / 7.2 = $2,462/oz-equivalent.
SGE silver Ag(T+D) — the trap
Ag(T+D) is quoted in CNY per gram but the contract unit is 15 kg. Do not confuse the two. The per-gram number is what matters for USD conversion; the 15-kg contract unit only affects position sizing.
Example: Ag(T+D) at 6.20 CNY/g, USD/CNY = 7.2. Convert: 6.20 × 31.1035 / 7.2 = $26.78/oz-equivalent. Do not multiply by 15,000 anywhere in this calculation.
Specific Traps to Avoid
⚠️ Common conversion errors
- Avoirdupois vs troy ounce. If a source is unclear which ounce it means, assume troy for gold. But verify — the ~10% difference is large enough to matter.
- Tola vs Nepalese tola. Nepal uses a "tola" that historically referred to a slightly different weight in some periods. Modern Nepalese jewelry retail uses the standard 11.66g tola but check with an old source.
- Baht for jewelry vs bullion. Thai jewelry baht is 15.244g; Thai bullion baht is 15.16g. The 0.5% difference matters for wholesale, less so for retail.
- Purity built into some retail quotes. Indian jewelers sometimes quote per-tola prices for 22-karat gold, not pure gold. Divide such quotes by 0.9167 to get the equivalent pure-gold-per-tola price.
- "Ounce" in scrap gold context. Scrap gold dealers in some Western countries quote in avoirdupois ounces because their scales use household units. This is the largest single source of retail confusion.
Purity and Weight Are Separate Concepts
Weight and purity are independent. A 22-karat gold coin might weigh 1 troy ounce total but contain only 22/24 = 91.67% pure gold by weight. Or it might be designed to contain exactly 1 troy ounce of pure gold plus additional copper alloy, making the total weight slightly higher than 1 troy oz. Both conventions exist for different products.
American Gold Eagles use the second convention: a 1-ounce American Gold Eagle contains exactly 1 troy oz of pure gold, with copper alloy adding to make the total coin weight 1.0909 troy oz. Krugerrands use the same convention. This is why coin weight specifications typically show both the pure-gold content and the total weight separately.
Canadian Maple Leafs and Chinese Pandas are 99.99% pure, so a 1-oz coin weighs almost exactly 1 troy oz overall. The difference matters for careful weight-based verification.
Practical Reference Table
📊 Quick reference table (rounded to 4 significant figures)
- 1 troy oz = 31.10 g = 2.667 tola = 0.9724 avoirdupois oz
- 1 kg = 32.15 troy oz = 85.75 tola
- 1 tola = 11.66 g = 0.3750 troy oz
- 1 bhori ≈ 1 tola ≈ 11.66 g
- 1 Thai baht (jewelry) = 15.24 g
- 1 Thai baht (bullion) = 15.16 g
What This Site Uses Internally
All prices on our dashboard are normalized to USD per troy ounce internally, using the exact conversion factor 31.1034768 g/troy oz. The local-price display for each market shows the quoted value in the market's native unit (INR/10g for MCX, CNY/g for SGE, GBP/oz for LBMA, USD/oz for COMEX) so that a reader can verify against a local price source. The USD/oz normalization is what enables premium calculation.
📌 Key Takeaways
- Six weight units are in current use for gold: troy oz, gram, kg, tola, bhori, and baht. Getting them right matters for cross-market comparison.
- 1 troy oz = 31.1035 g, exactly. Avoirdupois ounces (kitchen scales) are ~10% smaller — do not confuse them.
- 1 tola ≈ 1 bhori ≈ 11.66 g ≈ 0.375 troy oz. 1 kg ≈ 32.15 troy oz ≈ 85.75 tola.
- MCX quotes in INR/10g; SGE quotes in CNY/g; LBMA and COMEX quote in USD/oz. Our dashboard displays each in native unit and normalizes to USD/oz internally.
- Purity and weight are separate — a "1-ounce" 22-karat coin may weigh more or less than 1 troy oz depending on the design convention.
- Retail jewelry quotes are sometimes in 22-karat equivalents; convert by dividing by 0.9167 to get pure-gold-per-tola pricing.
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