Contents
How the ounces to grams converter works
Enter a mass in ounces or grams and the other field updates at once. Both unit menus can also switch to pounds, kilograms and other common mass units.
The exact conversion factor
This converter uses the international avoirdupois ounce, the ounce found in ordinary product and parcel weights. Its metric value is exact:
For the reverse conversion, divide grams by 28.349523125. The relationship follows from the international pound and is listed in the NIST mass conversion table. Calculations keep the full factor while the screen shows at most six decimal places.
Useful ounce and gram examples
- 1 oz = 28.349523 g. This is the exact factor rounded for display.
- 2.5 oz = 70.873808 g. Decimal ounce values work without an intermediate rounding step.
- 8 oz = 226.796185 g. Eight ounces are also half an international pound.
- 16 oz = 453.59237 g. Sixteen ounces make one international pound exactly.
An ounce is not always the same unit
An avoirdupois ounce measures mass. A fluid ounce measures volume, so it cannot be converted to grams unless the substance and its density are known. US and UK fluid ounces also have different volumes.
A troy ounce, commonly quoted for precious metals, equals 31.1034768 grams. Select or calculate with that unit only when the source explicitly says “troy oz”; the default oz here is the everyday avoirdupois ounce.
Questions about ounces and grams
These answers cover the factor, reverse calculation and the ounce types most often confused.
How many grams are in one ounce?
One international avoirdupois ounce is exactly 28.349523125 grams.
How do I convert ounces to grams by hand?
Multiply the number of ounces by 28.349523125. Round only after completing the multiplication.
How many ounces are in 100 grams?
One hundred grams are approximately 3.527396 avoirdupois ounces.
Is a fluid ounce equal to 28.35 grams?
No. A fluid ounce is a volume unit, and its mass in grams depends on the liquid and its density.
Does this converter use troy ounces?
No. The oz option is the ordinary avoirdupois ounce. One troy ounce is 31.1034768 grams.
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