What is Precise Grams ↔ Ounces Converter?
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Grams to Ounces Converter
Grams to ounces: 1 g = 0.0353 oz. Common in cooking, pharmacy, jewelry.
About this converter
The avoirdupois ounce (the regular cooking and packaging ounce in the US and UK) is exactly 28.349523125 grams. The gram is the SI gram, defined via the kilogram, which since 2019 is fixed by Planck's constant. For precious metals (gold, silver, platinum) the troy ounce of 31.1034768 g is used instead.
How it works
The 1959 International Yard and Pound Agreement fixed the avoirdupois pound at exactly 453.59237 grams. Dividing by 16 gives the ounce:
1 lb (avoirdupois) = 453.59237 g (exact)
1 oz (avoirdupois) = 453.59237 / 16
= 28.349523125 g (exact, NIST SP 811)
1 g = 1 / 28.349523125
= 0.03527396195 oz
1 troy oz = 31.1034768 g (exact)
= 1.09714286 avoirdupois oz
To convert: multiply grams by 0.03527396195 to get avoirdupois ounces; multiply ounces by 28.349523125 to get grams. For precious-metals work, swap in the troy factor.
Worked example
A US baker wants to follow a UK recipe that calls for 250 g of butter, 200 g of caster sugar, 4 eggs, and 250 g of self-raising flour. The kitchen scale only displays ounces (avoirdupois).
- Butter: 250 g x 0.03527396195 = 8.819 oz. Round to 8.8 oz, or use 8 oz + 23 g.
- Caster sugar: 200 g x 0.03527396195 = 7.055 oz, or roughly 7 oz.
- Self-raising flour: 250 g x 0.03527396195 = 8.819 oz, same as butter.
- Eggs are by count not weight, but a US large egg is 50 g, so 4 eggs = 200 g.
- Total weighed dry + butter: 250 + 200 + 250 = 700 g = 24.69 oz = ~1 lb 8.7 oz.
Reference table
| Grams | Avoirdupois oz | Troy oz | Equivalent |
|---|---|---|---|
| 1 g | 0.0353 oz | 0.0322 oz | One US dollar bill |
| 10 g | 0.353 oz | 0.322 oz | Two paperclips |
| 28.35 g | 1 oz | 0.911 oz | 1 avoirdupois oz |
| 31.10 g | 1.097 oz | 1 oz | 1 troy oz (gold coin) |
| 100 g | 3.527 oz | 3.215 oz | 1 standard chocolate bar |
| 250 g | 8.819 oz | 8.038 oz | ~1 US cup of butter (slightly more) |
| 453.59 g | 16 oz | 14.583 oz | 1 avoirdupois pound |
| 1,000 g | 35.274 oz | 32.151 oz | 1 kilogram |
Common pitfalls
- Avoirdupois vs troy ounce. 1 troy oz = 31.103 g; 1 regular (avoirdupois) oz = 28.350 g. The troy oz is about 10 percent heavier. Gold, silver, platinum, palladium, and rhodium prices use troy ounces exclusively. Confusing the two on a 1 oz gold coin valued at $2,500 is a $230 error.
- Fluid ounce is not mass. US fluid ounce = 29.574 mL of volume (US customary); UK fluid ounce = 28.413 mL. Fluid ounces measure volume, not weight. 8 fl oz of honey is heavier than 8 fl oz of water.
- "Cup" weights depend on the ingredient. Cups are volume; flour weighs 125 g/cup, sugar 200 g/cup, butter 227 g/cup. Recipe sites that just say "1 cup" without specifying the ingredient leave a 60 percent margin.
- "Ounce" in nutrition labels. US nutrition labels use the avoirdupois ounce (28.35 g) but for fluids switch to fluid ounces (29.57 mL). FDA "serving size" rounds to common household measures, not exact ounces.
- Local pound variants. "1 lb" in modern US/UK = 453.59237 g (avoirdupois). Apothecary pound and troy pound = 373.24 g (used historically in pharmacy and metals). Imperial pound is the same as US since 1959, but pre-1959 numbers can disagree by milligrams.
Related tools and references
Frequently asked questions
What is the exact gram to ounce conversion factor?
1 avoirdupois ounce is defined as exactly 28.349523125 grams, derived from the international avoirdupois pound (453.59237 g, by the 1959 International Yard and Pound Agreement) divided by 16. So 1 g = 0.03527396195 oz. NIST SP 811 lists the same exact value.
What is the difference between an avoirdupois ounce and a troy ounce?
Avoirdupois ounce (cooking, mail, body weight) = 28.349523125 g; 16 oz per avoirdupois pound. Troy ounce (precious metals only: gold, silver, platinum) = 31.1034768 g; 12 troy oz per troy pound. A troy ounce is about 10 percent heavier. Always check which is meant before pricing gold.
How many grams in a cup of flour or sugar?
Cups measure volume, not weight, so the gram value depends on the ingredient. Typical US cup: all-purpose flour 125 g (4.4 oz), whole-wheat flour 130 g, granulated sugar 200 g, brown sugar packed 220 g, butter 227 g (half a US pound). Spoon flour into the cup and level off; scooping packs it tight and overweights by 15 percent.
How is the kilogram defined today?
Since 20 May 2019 the kilogram has been defined by fixing the numerical value of Planck's constant h = 6.62607015 x 10^-34 J*s (BIPM CGPM 2018). The old International Prototype Kilogram (IPK), a platinum-iridium cylinder kept in Sevres since 1889, is no longer a defining standard.
Sources
- International Yard and Pound Agreement (1959), 1 lb = 0.45359237 kg.
- NIST Special Publication 811 (2008) Guide for the Use of the International System of Units, App. B.8.
- BIPM CGPM (2018) Revision of the SI, redefinition of the kilogram via Planck's constant, effective 20 May 2019.
- LBMA Good Delivery rules - troy ounce of 31.1034768 g.