Ounce to Gram Converter
Our free volume & weight converter handles ounce gram conversions. See tables, ratios, and examples for quick reference.
Formula
Grams = Ounces x 28.3495 (avoirdupois) or x 31.1035 (troy)
Multiply ounces by 28.3495 for standard avoirdupois ounces, or by 31.1035 for troy ounces used with precious metals. Divide grams by the same factor for the reverse conversion.
Worked Examples
Example 1: Cooking Ingredient Conversion
Problem:A recipe calls for 6 ounces of chocolate. How many grams is that?
Solution:Grams = 6 oz x 28.3495 g/oz = 170.097 grams Kilograms = 170.097 / 1000 = 0.170 kg Pounds = 6 / 16 = 0.375 lb
Result:6 oz = 170.097 grams
Example 2: Gold Weight Conversion
Problem:A gold bar weighs 100 grams. How many troy ounces is that?
Solution:Troy ounces = 100 g / 31.1035 g/troy oz = 3.2151 troy oz Avoirdupois ounces = 100 / 28.3495 = 3.5274 oz Carats = 100 x 5 = 500 carats
Result:100 grams = 3.2151 troy ounces
Frequently Asked Questions
How many grams are in an ounce?
One avoirdupois ounce (the standard ounce used for food and everyday items) equals 28.3495 grams. One troy ounce (used for precious metals like gold and silver) equals 31.1035 grams. The avoirdupois ounce is by far the more common measurement and is what people typically mean when they say ounce. The difference between the two is about 10%, which is significant when buying or selling precious metals.
What is the difference between avoirdupois and troy ounces?
Avoirdupois ounces are the standard ounces used in everyday life for food, postage, and general weight measurements. There are 16 avoirdupois ounces in a pound. Troy ounces are heavier at 31.1035 grams versus 28.3495 grams and are used exclusively for precious metals, gemstones, and some pharmaceuticals. There are 12 troy ounces in a troy pound. When gold is quoted at a certain price per ounce, it always refers to troy ounces.
How do I convert ounces to grams for cooking?
For cooking, multiply ounces by 28.35 to get grams. Common kitchen conversions include: 1 oz = 28.35 g, 4 oz = 113.4 g (quarter pound), 8 oz = 226.8 g (half pound), and 16 oz = 453.6 g (one pound). Many kitchen scales can switch between ounces and grams. For baking, using grams provides more precision since small differences in ingredient amounts can affect the outcome significantly.
Why do some countries use grams and others use ounces?
Most countries worldwide use the metric system with grams and kilograms as standard weight measurements. The United States, Liberia, and Myanmar are the only countries that have not officially adopted the metric system for everyday use. The US still primarily uses ounces and pounds for food labeling, cooking, and commerce. However, US food labels are required to show both ounces and grams, and scientific work in the US uses metric exclusively.
Why do US recipes measure by volume in cups while European recipes measure by weight in grams?
The difference is largely historical rather than practical. American home cooking developed around standardized measuring cups and spoons that were cheap to manufacture and easy to teach, so recipes settled on volume measures for convenience. European and professional baking traditions favor weight because a gram of flour is the same regardless of how it is scooped or packed, while a cup of flour can vary by 20 percent or more depending on whether it was sifted, spooned, or scooped directly from the bag. For baking specifically, where ratios of flour, fat, and liquid must be precise, weighing ingredients in grams (or ounces on a kitchen scale) produces far more consistent results than volume measuring, which is why professional bakers and most European cookbooks specify weight.
Why is the avoirdupois ounce defined as exactly 28.349523125 grams?
The value is exact by definition, not by measurement. Since the 1959 International Yard and Pound Agreement, the avoirdupois pound is defined as exactly 0.45359237 kilograms. An avoirdupois ounce is one sixteenth of that pound, so 0.45359237 kg divided by 16 gives 0.028349523125 kg, or 28.349523125 grams. Rounding to 28.3495 g is accurate to about one part in ten million, far finer than any kitchen or postal scale can resolve.
How do carats relate to grams when weighing gemstones?
The metric carat used for gemstones is defined as exactly 0.2 grams, so one gram equals 5 carats. That is why the converter multiplies grams by 5. Do not confuse the metric carat, a unit of mass, with the karat used for gold purity, which is a fraction out of 24 and carries no weight meaning at all. A 2 carat diamond therefore weighs 0.4 grams, or roughly 0.0141 avoirdupois ounces.
Why do precious metal dealers quote prices in troy ounces rather than grams?
Troy weight survives from medieval bullion trading and became the entrenched standard for gold, silver, platinum and palladium, so spot prices, futures contracts and bar sizes are all quoted per troy ounce. Because a troy ounce is 31.1035 g against the avoirdupois 28.3495 g, treating a bullion quote as an everyday ounce understates the metal by about 9.7 percent. To compare a gram priced item with a spot quote, divide the spot price by 31.1035 first.
When should I weigh an ingredient in milligrams instead of grams?
Milligrams become useful once a quantity falls below roughly one gram, where a scale reading only to 0.1 g introduces large percentage error. Supplements, spices, leavening agents, curing salts and pharmacy compounding are specified in milligrams for that reason. One gram is 1000 milligrams, and one avoirdupois ounce is 28349.5 milligrams. Milligram work needs a balance with readability of 0.001 g or finer plus a draft shield to stay stable.
What is the difference between net weight and drained weight on a package label?
Net weight is the mass of the product excluding all packaging, and it is the figure US labels show in both ounces and grams. Drained weight applies to canned or brined goods and states only the solid contents after the packing liquid is poured off, so it is always the smaller number. When converting a recipe calling for a weight of canned beans or tuna, check which figure it assumes, because the gap between the two can reach 30 to 40 percent.
References
Background & Theory
1 avoirdupois ounce = 28.349523125 grams exactly; 1 troy ounce = 31.1034768 grams exactly. Both are definitions rather than measured ratios, and choosing the wrong one changes the answer by about 9.7 percent.
Conversion reference table
| Conversion | Equivalent | Exact or rounded? |
|---|---|---|
| 1 ounce (avoirdupois) | 28.349523125 grams | Exact - food, post, general use |
| 1 troy ounce | 31.1034768 grams | Exact - bullion and gemstones |
| 1 pennyweight (1/20 troy oz) | 1.55517384 grams | Exact |
| 1 grain | 64.79891 milligrams | Exact - shared by both systems |
| 1 avoirdupois pound | 16 oz = 453.59237 grams | Exact |
| 1 troy pound | 12 troy oz = 373.2417216 grams | Exact |
| 1 metric carat | 200 milligrams | Exact - gemstones |
The grain is the hinge between the two systems: the avoirdupois ounce is 437.5 grains and the troy ounce is 480 grains, and a grain is exactly 64.79891 mg in both. That is why a bullion dealer quoting a price per ounce and a grocer quoting a price per ounce are not quoting the same quantity of metal, and why spot gold is always stated per troy ounce.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator ยท Editorial policy
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