Article — Grams to Ounces Converter
Grams to ounces: convert g to oz exactly
One gram equals 0.035274 avoirdupois ounces. One avoirdupois ounce equals exactly 28.349523125 grams — a defined value, not a measurement. Almost every conversion you need uses these two numbers and nothing else. The exception is gold and silver, which trade in troy ounces (31.1035 grams), about 9.7% heavier than the ounce that shows up everywhere else.
The calculator at the top of this page handles both ounce types and converts in either direction. The article below explains where the numbers come from and which one to use when.
What is a gram?
A gram is one one-thousandth of a kilogram. The kilogram is the SI base unit of mass, and since May 2019 it has been defined by the Planck constant rather than by a physical reference object. That means the gram is now a quantity grounded in quantum mechanics, not in a metal cylinder stored in a vault outside Paris.
Grams are the everyday metric unit for weighing food, postage, jewelry, and small objects. In a recipe, "200 g flour" is a direct mass measurement that does not depend on the size of your measuring cup or the way you packed it. That precision is the main reason European cooks prefer the metric system for baking.
For 130 years the kilogram was a physical object: a platinum-iridium cylinder kept in a vault near Paris called Le Grand K. It was the only SI unit defined by a manufactured artifact. The problem was that Le Grand K kept losing atoms — its mass had drifted by about 50 micrograms over a century. In 2019 the kilogram was redefined using the Planck constant, ending the era of measurement by reference object.
What is an ounce?
An ounce is a unit of mass. The complication is that there are two of them, and they are nearly identical in name but different in size.
The avoirdupois ounce is the everyday ounce. It equals exactly 28.349523125 grams — the value you get by dividing the international pound (453.59237 g) by 16. It is what your food scale measures, what the post office charges by, and what shows up on a US nutrition label.
The troy ounce is the precious-metals ounce. It equals 31.1034768 grams — about 9.7% heavier. It is used only for gold, silver, platinum, palladium, and a handful of historical pharmacy contexts. When you read "gold is $2,000 an ounce," that ounce is the troy one.
The grams to ounces formula
To convert grams to avoirdupois ounces, divide by 28.349523125. To convert ounces to grams, multiply by the same number.
oz = g ÷ 28.3495 (avoirdupois)g = oz × 28.3495 (avoirdupois)oz = g ÷ 31.1035 (troy)g = oz × 31.1035 (troy)The factor 28.349523125 is exact, derived from the 1959 International Yard and Pound Agreement that fixed one international pound at exactly 453.59237 g. Sixteen ounces in a pound gives the per-ounce mass. Any conversion that uses more than nine decimal places is reporting a different ounce — usually the older US customary or imperial values that were superseded in 1959.
Avoirdupois vs. troy ounce
The two ounces look almost identical on the surface and produce wildly different answers in practice. The numbers below are exact:
Beyond the ounce difference, the pounds work the other way. An avoirdupois pound has 16 ounces and weighs 453.6 g. A troy pound has only 12 ounces and weighs 373.2 g. So the troy ounce is heavier, but the troy pound is lighter. It is the kind of historical quirk that turns metric loyalists smug.
If you accidentally use 28.35 g for a gold weight, you understate the true mass by 9.7%. On 10 ounces of gold (currently around $20,000), the gap is roughly $2,000. Always confirm: precious metals → troy. Everything else → avoirdupois.
Common grams to ounces conversions
The most-searched values, computed at the exact avoirdupois factor:
- 1 g = 0.0353 oz (a paper clip)
- 5 g = 0.1764 oz (a teaspoon of sugar)
- 28.35 g = exactly 1 oz
- 100 g = 3.5274 oz (a chocolate bar)
- 113.4 g = exactly 4 oz (¼ lb, raw burger patty)
- 200 g = 7.055 oz
- 250 g = 8.819 oz
- 453.6 g = exactly 16 oz = 1 lb
- 500 g = 17.637 oz (half a kilo)
- 1,000 g = 35.274 oz (one kilogram, about 2.2 lb)
Mental-math shortcut: divide grams by 28 (close enough) or by 30 (easier division, slightly less accurate). For a precise answer the calculator above is faster than the head math.
Cooking with grams and ounces
Recipe conversions almost always use the avoirdupois ounce. A "4 oz" portion in any cookbook means 113 grams. A "1 oz" measure of cheese is 28 grams.
The tricky case in cooking is that US recipes sometimes use the same word "ounce" for both mass and volume. A "1 oz" weight of flour is 28 g. A "1 fl oz" volume of milk is 29.57 mL. Both abbreviate to "oz" in casual writing, and they only match for water at room temperature. For anything denser than water (honey, syrup, melted butter) or lighter than water (oil, flour, sugar), the gap is significant. Always check whether the recipe means weight or volume — and prefer weight when the difference matters.
If you bake regularly, buy a digital kitchen scale and switch to grams. A 200 g flour measurement is far more repeatable than "1.5 cups" — flour packs unevenly and a 1.5 cup measurement can vary by 30 g between attempts. Professional bakers worldwide weigh ingredients for this reason.
Gold and precious metals
Gold, silver, platinum, and palladium are quoted, traded, and sold in troy ounces — 31.1 grams each. A gold price of "$2,000 per ounce" means $2,000 per troy ounce, which works out to about $64.30 per gram.
This is one of the few areas where the older measurement survived the metric system entirely. London bullion pricing has used troy ounces since 1973. New York COMEX gold futures, the LBMA Gold Price, and every spot quote on the screen all use troy ounces. There is no scenario in modern precious-metals commerce where avoirdupois ounces apply.
The word "troy" has nothing to do with ancient Troy. It comes from Troyes, a French city in the Champagne region that hosted Europe's largest medieval trade fairs from the 12th century onward. Merchants from across the continent traded gold, silver, and spices there, and they standardised the troy ounce as the unit of precious-metals weight. The word has outlasted the fairs by about 700 years.
Common grams-to-ounces mistakes
Using troy ounces for cooking. A recipe never asks for troy ounces. If you weigh 4 troy oz of flour instead of 4 avoirdupois oz, you have 124 g instead of 113 g — about 10% more.
Using avoirdupois ounces for gold. The opposite mistake. If you weigh 10 oz of gold on an avoirdupois scale and price it at the troy spot price, you understate the value by 9.7%.
Confusing oz with fl oz. Mass versus volume. They only agree for water at room temperature. For oil, syrup, milk, or anything else, an "8 oz" by weight is meaningfully different from "8 fl oz" by volume.
Rounding 1 oz to 28 g. Fine for cooking. Wrong for legal weights, postage, or pharmacy work. Use the full 28.3495 g when accuracy matters.