⚖️ Troy vs Avoirdupois Decoder

Grams to Ounces Converter: Troy Ounce vs Avoirdupois Ounce Decoder for Gold and Silver, FDA Nutrition Label Serving Size Context, and EU Package Label Reference

Three modes: convert grams to avoirdupois oz for food and shipping (1 oz = 28.349523125 g exact), use Precious Metals mode for troy oz conversion critical for gold and silver pricing (1 troy oz = 31.1034768 g), or batch-convert up to 20 values. Includes FDA nutrition label serving size context and UK/India gold unit references.

1 av oz = 28.349523125 g exact 1 troy oz = 31.1034768 g FDA Label Serving Size Context Gold Bar Reference Sizes Pennyweight and Grain Batch up to 20 Values
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Grams to Ounces

g
Food oz (avoirdupois): 1 oz = 28.349523125 g. 28g = 0.9877 oz (FDA rounds to 1 oz). 85g = 2.999 oz (FDA 3-oz meat ref). 100g = 3.527 oz. For gold: use Precious Metals tab (1 troy oz = 31.1035g).

Conversion Result

0 oz
0 grams input
0 troy oz
0 pounds

Formula and Context

The Troy Ounce vs Avoirdupois Ounce Problem That Trips Up American Consumers, Jewelers, and Import Sellers

The word “ounce” means two completely different things depending on what you are weighing. When a US nutrition label says “serving size 1 oz (28g),” it is using the avoirdupois ounce, which equals 28.349523125 grams exactly. When a coin dealer or gold broker quotes a price per ounce, they mean the troy ounce, which equals 31.1034768 grams exactly. The troy ounce is heavier than the avoirdupois ounce by 2.75 grams, which is about 9.7%. That 9.7% difference is enormous when you are talking about gold at over $3,000 per troy ounce.

This distinction causes real financial errors. A buyer who sees a “5-ounce silver bar” at a coin shop and assumes it weighs 5 x 28.349 = 141.75 grams is wrong. It actually weighs 5 x 31.103 = 155.517 grams. That is 13.77 grams of silver they did not account for. At scale, a wholesaler purchasing 100 troy ounces of gold who uses the avoirdupois conversion will miscalculate their position by 100 x (31.103 – 28.349) = 275.4 grams = 8.857 troy oz = a significant pricing error. The London Bullion Market Association (LBMA), the New York Mercantile Exchange (NYMEX/COMEX), and the US Mint all price gold, silver, platinum, and palladium exclusively in troy ounces. The gram is the SI base unit, and this calculator provides exact conversion between grams and both ounce systems.

For food and everyday weights, the avoirdupois ounce (28.349523125 g) is what matters. This is derived directly from the 1959 International Pound: 1 lb = 453.59237 g, and there are 16 ounces per pound, so 1 oz = 453.59237/16 = 28.349523125 g exactly. NIST documents this at NIST.gov. For precious metals, use the troy ounce (31.1034768 g, exact from 1 troy lb = 5760 grains and 1 grain = 0.06479891 g).

1 av oz = 28.3495 g Food/shipping oz. 1 lb = 453.59237 g / 16 = 28.349523125 g. 1 g = 0.035274 oz.
1 troy oz = 31.1035 g Gold/silver oz. 9.7% heavier than av oz. 100g = 3.2151 troy oz. 1 kg gold bar = 32.151 troy oz.
FDA: 85g = 3 oz FDA reference serving for meat/poultry/seafood is 85g = 2.999 av oz, labeled as 3 oz. 28g = label shorthand for 1 oz.

How the Three-Mode Grams to Ounces Converter Works

Mode 1: Single Grams to Avoirdupois Oz (Food and Shipping)

Enter any gram value or select from FDA serving size presets (28g, 30g, 57g, 85g, 100g, 113g) or EU food packaging presets (200g, 250g, 500g, 1000g). Output: avoirdupois oz, troy oz, pounds, grams, pennyweight, and grains. If the gram value matches an FDA reference serving amount, a note explains the FDA nutrition label context. Chart compares input to 1 av oz (28.35g), 1 troy oz (31.10g), the FDA 3-oz meat reference (85g), and the EU 100g reference.

Mode 2: Precious Metals Mode (Troy Oz)

Enter grams of gold, silver, platinum, or palladium. Output: troy oz (the unit used for all precious metal pricing globally), avoirdupois oz (for comparison), pennyweight, grains, and tola (Indian gold unit). Approximate spot value in USD shown at the gold price as of the last update. Always verify live spot price at LBMA or a real-time market source. Chart compares the input to 1 troy oz (31.10g), a 100g gold bar, and a 400g LBMA London Good Delivery bar.

Mode 3: Batch Conversion

Enter up to 20 gram values (one per line). Table shows avoirdupois oz, troy oz, pounds, and pennyweight for each. Useful for converting a list of EU product weights for FDA-compliant US labeling, or a jewelry inventory of gram weights to troy oz for pricing.

Troy Ounce vs Avoirdupois Ounce and FDA Nutrition Label Gram Reference Table

Troy vs Avoirdupois: Critical Difference for Precious Metals

UnitGramsContextNotes
1 avoirdupois oz28.349523125 gFood, shipping, body weightFDA, USPS, grocery stores, recipes
1 troy oz31.1034768 gGold, silver, platinum, palladiumLBMA, COMEX, US Mint, jewelry trade
Difference2.753954 g more per troy oz9.714% heavier1 troy oz = 1.09714 avoirdupois oz
1 pennyweight (dwt)1.55517384 gJewelry, dental gold1 troy oz = 20 dwt
1 grain0.06479891 gBullets, powder, pharmacy1 troy oz = 480 grains; 1 av oz = 437.5 grains
1 tola11.6638038 gIndia gold market1 tola = 3/8 troy oz = 11.66g

FDA Nutrition Label Reference Amounts (RACC) in Grams and Oz

FDA RACC CategoryGramsExact oz (av)Label oz
Chips, crackers, popcorn, nuts28 g0.9877 oz“1 oz (28g)” — FDA rounds
Breakfast cereals (ready-to-eat)30 g1.058 oz“1 oz (30g)” or “about 1 cup”
Meat, poultry, seafood reference85 g2.999 oz“3 oz (85g)”
EU food label reference amount100 g3.527 ozEU uses 100g as standard
Deli meats, sliced57 g2.011 oz“2 oz (57g)”
Cheese, natural30 g1.058 oz“1 oz (30g)” or about 1.5-inch cube

FDA Reference Amounts Customarily Consumed (RACC) from 21 CFR Part 101, available at FDA.gov/food. EU reference amounts from EU Food Information to Consumers Regulation 1169/2011. The FDA rounds 28.349523125 g to 28g for the “1 oz” label — a simplification used since 1994.

Three Real US Examples: EU Cookie Import Labeling, 100g Gold Bar Value, and Recipe Conversion

Example 1: Converting a 200g EU Cookie Package to US Oz for FDA-Compliant Import Labeling

Conversion: 200 g / 28.349523125 = 7.055 av oz. FDA label: “7.05 oz (200g)”. Serving size calculation at 7 servings of 28g each.

A Texas importer is bringing in a Belgian cookie brand for US retail distribution. Each package contains 200g of cookies. The EU package shows only the metric net weight (200g). For US retail sale, FDA requires the net quantity statement on the principal display panel to use avoirdupois ounces for packages under 1 pound.

Single conversion: 200g / 28.349523125 = 7.0548 av oz. The FDA label must state “7.05 oz (200g).” Serving size per cookie: if each cookie weighs approximately 28g (close to 1 oz), the package contains about 7 servings. The FDA’s 1 oz RACC for cookies and crackers means each 28g serving = 0.9877 oz (labeled as “1 oz (28g)” using FDA rounding). The package has 7 full servings at 28g each = 196g, with 4g left — so it might be declared as 7 servings of 28g or adjusted to a different serving size. For FDA-compliant nutrition facts panel setup, see the FDA’s nutrition labeling guidance at FDA.gov/food. NIST Handbook 130 net content regulations at NIST.gov.

Example 2: A First-Time Gold Buyer Converting a 100g Gold Bar to Troy Oz and Checking the Value

Conversion: 100g / 31.1034768 = 3.2151 troy oz. Approximate value at $3,340/troy oz: $10,738.

A Colorado Springs investor is buying their first physical gold bar. They are comparing a 100g gold bar to a 3-troy-oz bar. They want to know whether 100g gives them more or less gold than 3 troy oz, and what the approximate value is.

Precious Metals mode: 100g / 31.1034768 = 3.2151 troy oz. A 3 troy oz bar = 3 x 31.1034768 = 93.310g. So a 100g bar contains more gold than a 3-troy-oz bar (3.2151 troy oz vs exactly 3 troy oz, a difference of 6.69g = 0.2151 troy oz). At a gold spot of approximately $3,340/troy oz (as of mid-2025), a 100g bar is worth approximately 3.2151 x $3,340 = $10,738 at spot. A 3-troy-oz bar at spot = 3 x $3,340 = $10,020. The CRITICAL error to avoid: do NOT convert 100g using the avoirdupois factor (28.3495g/oz), which would incorrectly give 3.527 oz — that is wrong for gold, which is always priced per troy oz. Live gold prices at London Bullion Market Association at LBMA.org.uk. COMEX gold futures at CMEGroup.com.

Example 3: Converting a French Recipe from Grams to US Cups and Oz

Batch: 250g flour = 8.818 oz. 200g butter = 7.055 oz. 150g sugar = 5.291 oz. 100g chocolate = 3.527 oz. 30g cocoa = 1.058 oz.

A home baker in Nashville is making a French chocolate cake. The recipe calls for 250g flour, 200g butter, 150g sugar, 100g dark chocolate, and 30g cocoa powder. US measuring cups work in volume, not mass, but many US bakers weigh ingredients in ounces using a kitchen scale.

Batch conversion: 250g flour = 250 / 28.349523125 = 8.818 oz. 200g butter = 7.055 oz. 150g sugar = 5.291 oz. 100g chocolate = 3.527 oz. 30g cocoa = 1.058 oz. Cross-check: 30g / 28.349523125 = 1.058 oz, labeled as “about 1 oz” on a US kitchen scale set to oz. For volume approximations: 250g all-purpose flour is roughly 2 cups (varies by flour type and how it was scooped). 200g butter = 7 oz = about 14 tablespoons = 7/8 cup. 150g granulated sugar = about 3/4 cup. For US baking, a digital kitchen scale reading in both grams and oz is ideal. For EU recipe conversion resources, see the USDA’s weight-volume tables for common foods at USDA.gov.

Expert Tips: Why FDA Rounds 28.349g to 28g, How Gold Dealers Quote Prices, and EU vs US Recipe Scaling

Tip 1: Why FDA Nutrition Labels Say “1 oz (28g)” Instead of “1 oz (28.35g)”

The FDA’s nutrition labeling regulations (21 CFR Part 101) allow rounding gram values in the net quantity statement and serving size declaration. When a food company declares a serving size of 28.349523125 grams, the FDA permits rounding to the nearest whole gram for the parenthetical metric equivalent. So “1 oz” = 28.349… g rounds to 28g on the label. This rounding is legal and standard, but it creates a widespread consumer misconception that 1 oz exactly equals 28 grams. It does not. The exact value is 28.349523125 g. For most cooking and nutrition purposes, the 0.35g rounding error per ounce is completely negligible. But for FDA net quantity compliance on packages, importers must state the actual net weight, not the rounded serving size: a 200g package must say “7.05 oz (200g),” not “7 oz (200g).” The FDA guidance on rounding and net quantity declarations is in 21 CFR 101.105 at FDA.gov/food.

Tip 2: How Gold Dealers Quote Prices and Why the Troy Oz Error Costs Real Money

When you see a gold price on Bloomberg, Kitco, or CNBC — say $3,340 per ounce — that price is always per troy ounce (31.1034768 g). It is never per avoirdupois ounce (28.349523125 g). The LBMA Gold Price, set twice daily in London, and the COMEX gold futures contract on the CME Group, both denominate in troy ounces. A 1-kilogram gold bar (1,000 g) contains 1,000 / 31.1034768 = 32.1507 troy oz, not 1,000 / 28.3495 = 35.274 avoirdupois oz. At $3,340/troy oz, the 1-kg bar is worth 32.1507 x $3,340 = $107,383. Using the wrong ounce gives $35.274 x $3,340 = $117,815 — a $10,432 error on a single bar. For jewelry, the situation is more nuanced: retail jewelry is often marked in avoirdupois oz for consumer weight, but gold content is priced in troy oz by the jewelry trade. When a jeweler buys gold at “spot,” spot is troy oz. LBMA publishes live gold prices at LBMA.org.uk.

Tip 3: Indian Gold Market Uses Tola: 1 Tola = 11.6638 g = 0.375 Troy Oz

The Indian subcontinent gold market (India, Pakistan, Bangladesh) traditionally measures gold in tola. 1 tola = 3/8 troy oz = 3/8 x 31.1034768 = 11.6638038 g exactly. A 10-tola gold bar = 10 x 11.6638 = 116.638 g = 116.638 / 31.1034768 = 3.75 troy oz. India is the world’s second-largest gold consumer, and Indian investors buying gold through US dealers or online platforms may need to convert tola to grams and troy oz for pricing. A common Indian gold bar: 100g = 100 / 11.6638038 = 8.573 tola = 3.2151 troy oz. The World Gold Council publishes demand and pricing data for the Indian market at gold.org. US Customs and CBP value gold imports in troy oz per Schedule B classification codes.

Tip 4: Bullet and Powder Grains vs Food Grams: The Same Word “Grain” Means the Same Thing

A grain is the smallest unit in both the avoirdupois and troy weight systems, and it has the same definition in both: 1 grain = 0.06479891 g exactly (1/7000 avoirdupois pound = 453.59237/7000). Firearm ammunition is sold in grains: a 9mm 115-grain bullet = 115 x 0.06479891 = 7.452 g = 0.2629 av oz. A 300-grain .30-06 projectile = 300 x 0.06479891 = 19.44 g = 0.686 av oz. Powder charges are also in grains: a 6-grain powder charge = 6 x 0.06479891 = 0.389 g. Pharmaceutical apothecary weights also use grains (though this system is largely obsolete in the US). The ATF regulates ammunition commerce; SAAMI (Sporting Arms and Ammunition Manufacturers’ Institute) publishes cartridge specifications in grains at SAAMI.org. The key: in the context of this calculator, “grain” for precious metals and ammunition means the same mass unit: 0.06479891 g.

The practical reality of grams-to-ounces conversion in the US is that it appears constantly in three very different industries: food manufacturing and retail, precious metals trading, and pharmaceutical compounding. In food, the EU metric gram is the global standard, but the US market demands avoirdupois ounces and pounds for retail shelf labeling. An EU food manufacturer exporting to the US must convert every weight on their packaging. A 750g wine bottle of olive oil becomes 26.46 oz (1 lb 10.46 oz) on the US label. A 450g pasta package becomes 15.87 oz. A 330ml beer can (which converts to 330g for water, but beer weighs slightly more) is sold in the US as an “11.2 fl oz” can, where the fluid ounce is a volume measure — different from the weight ounce, a confusion the US measurement system creates that no other country deals with. In precious metals, every gram of gold or silver must be priced in troy ounces, requiring the exact factor 31.1034768 g/troy oz. In pharmacy, drug compounding in the US uses both metric and apothecary measures, where grains appear in prescriptions for some older formulations (thyroid medication is still sometimes dosed in grains). The FDA’s National Drug Code system and the USP both recognize grains as a valid US unit for drug labeling where historical precedent exists. The USDA’s Agricultural Marketing Service reports crop weights in both metric tons (for international trade data) and US short tons, pounds, and ounces (for domestic market reports). These parallel systems coexist because US commerce operates simultaneously in domestic customary units and international metric units, and the only way to move accurately between them is with exact conversion factors. For any application where errors have financial or safety consequences, the 28.349523125 g per avoirdupois oz and 31.1034768 g per troy oz are the values that matter — not rounded approximations.

Quick Reference: Common Gram Values Converted to Avoirdupois Oz and Troy Oz

GramsAv oz (food)Troy oz (gold)PoundsUS Context
1 g0.03527 av oz0.03215 troy oz0.0022 lbs1g gold bar (entry bullion)
28.35 g1.000 av oz0.9116 troy oz0.0625 lbsExact 1 av oz (FDA rounds to 28g)
31.10 g1.097 av oz1.000 troy oz0.0686 lbsExact 1 troy oz (gold pricing unit)
85 g2.999 av oz2.733 troy oz0.1874 lbsFDA 3-oz meat/poultry/seafood ref
100 g3.527 av oz3.215 troy oz0.2205 lbsEU food label ref; 100g gold bar
200 g7.055 av oz6.430 troy oz0.4409 lbsEU 200g food package
250 g8.818 av oz8.038 troy oz0.5512 lbsEU quarter-kilo; 1 cup flour approx
400 g14.110 av oz12.860 troy oz0.8818 lbsLBMA London Good Delivery gold bar
500 g17.637 av oz16.076 troy oz1.102 lbsEU half-kilo package
1,000 g35.274 av oz32.151 troy oz2.205 lbs1 kg gold bar = 32.151 troy oz

Formula: av oz = g / 28.349523125. Troy oz = g / 31.1034768. Source: NIST at NIST.gov; FDA nutrition label requirements at FDA.gov/food; LBMA gold pricing at LBMA.org.uk.

Frequently Asked Questions: Grams to Ounces

100 g = 100 / 28.349523125 = 3.527 oz (avoirdupois, food). For gold: 100 g = 100 / 31.1034768 = 3.215 troy oz. The EU uses 100g as a standard nutrition reference amount; US labels would convert to 3.53 oz.
200 g = 200 / 28.349523125 = 7.055 oz (avoirdupois). For gold: 200g = 6.430 troy oz. A 200g EU food package is labeled “7.05 oz (200g)” on the US retail label.
500 g = 500 / 28.349523125 = 17.637 oz = 1.102 lbs (avoirdupois). For gold: 500g = 16.076 troy oz. A 500g EU package is labeled “17.64 oz (500g)” or “1 lb 1.64 oz (500g)” in the US.
1000 g (1 kg) = 35.274 oz = 2.205 lbs (avoirdupois). For gold: 1000g = 32.151 troy oz. A 1-kilogram gold bar is worth approximately 32.151 x current gold spot price in USD.
The exact avoirdupois ounce is 28.349523125 g (453.59237 / 16). FDA nutrition labels round this to 28g for simplicity. So a label saying “1 oz (28g)” uses rounded values. The exact 1 oz = 28.3495g, not exactly 28g. For gold, 1 troy oz = 31.1034768g (a completely different, heavier ounce).
250 g = 250 / 28.349523125 = 8.818 oz (avoirdupois). For gold: 250g = 8.038 troy oz. A 250g block of EU butter is 8.82 oz in US units (about half a pound plus a little).
For food (avoirdupois): oz = g / 28.349523125. Quick estimate: divide by 28.35. For gold/silver (troy): troy oz = g / 31.1034768. Quick estimate: divide by 31.10. Never use the food formula for gold pricing.
28 g = 28 / 28.349523125 = 0.9877 oz (NOT exactly 1 oz). FDA nutrition labels round 28.3495g down to 28g, creating the impression that 28g = 1 oz. The exact 1 oz = 28.349523125g.
100 g = 100 / 31.1034768 = 3.2151 troy oz. This is for precious metals only. For food weight, 100g = 3.527 avoirdupois oz. Never use troy oz for food labeling.
150 g = 150 / 28.349523125 = 5.291 oz (avoirdupois). For gold: 150g = 4.823 troy oz. A 150g portion of protein is about 5.3 oz in US terms.
50 g = 50 / 28.349523125 = 1.764 oz (avoirdupois). For gold: 50g = 1.608 troy oz. A 50g portion (nearly 2 oz) is a common serving size for deli items.
300 g = 300 / 28.349523125 = 10.582 oz (avoirdupois). For gold: 300g = 9.645 troy oz. A 300g steak is about 10.6 oz, often listed on menus as “10-oz.”
1 g = 1 / 28.349523125 = 0.035274 oz (avoirdupois). For gold: 1g = 1 / 31.1034768 = 0.032151 troy oz. A 1g gold bar is a popular entry-level gold investment product.
85 g = 85 / 28.349523125 = 2.9983 oz, essentially 3 oz. The FDA uses 85g as the reference amount for meat, poultry, and seafood serving sizes, labeled as “3 oz” on nutrition facts panels.
30 g = 30 / 28.349523125 = 1.058 oz (avoirdupois). Just over 1 oz. The FDA uses 30g as the reference amount for most ready-to-eat breakfast cereals, labeled as “1 oz (30g).”
170 g = 170 / 28.349523125 = 5.997 oz, essentially 6 oz (avoirdupois). A 170g chicken breast or salmon fillet is a standard 6-oz portion in US restaurant cooking.
400 g = 400 / 28.349523125 = 14.110 oz (avoirdupois). For gold: 400g = 12.860 troy oz. The LBMA London Good Delivery standard gold bar ranges 350-430g, with the benchmark center at 400g = 12.86 troy oz.
10 g = 10 / 28.349523125 = 0.353 oz (avoirdupois). For gold: 10g = 0.3215 troy oz. The 10g gold bar is one of the most popular retail bullion sizes in the US market.
56 g = 56 / 28.349523125 = 1.975 oz, just under 2 oz (avoirdupois). The FDA reference amount for a 2-oz serving is 57g = 2.011 oz.
400g of gold = 400 / 31.1034768 = 12.860 troy oz. This is the standard London Good Delivery bar size. Always use troy oz for gold — never avoirdupois oz. At ~$3,340/troy oz, a 400g bar is worth approximately $42,952 at spot.

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Legal Disclaimer and Editorial Transparency

The Grams to Ounces Converter on USCalculators.com is provided for educational and informational purposes only. Avoirdupois ounce: 1 oz = 28.349523125 g exactly (1 lb = 453.59237 g / 16 oz, exact under 1959 International Pound Agreement). Troy ounce: 1 troy oz = 31.1034768 g exactly (from 1 grain = 0.06479891 g exact, 1 troy oz = 480 grains). Gold spot price reference (~$3,340/troy oz) is an approximate figure as of August 2025 for illustrative purposes only; actual gold prices fluctuate continuously. Always verify live precious metal prices at LBMA.org.uk or a licensed broker before any transaction. FDA nutrition label reference amounts (RACC) from 21 CFR Part 101, subject to FDA updates; verify current requirements at FDA.gov/food. Tola definition (11.6638038g) from traditional Indian measurement standards; may vary slightly by regional convention. This calculator does not provide financial, investment, commodity trading, or pharmaceutical dosing advice. All conversions for commercial labeling, gold trading, pharmaceutical applications, or regulatory filings should be verified with the applicable authority. Outbound links to NIST.gov, FDA.gov, LBMA.org.uk, CMEGroup.com, gold.org, and USDA.gov are provided for informational authority only.