Grams to Ounces: The Complete Guide
Grams (g) and ounces (oz) are both used for small weights — food portions, postal weights, precious metals, and pharmaceutical measurements. The ounce used for everyday weight (food, parcels) is the avoirdupois ounce. A different unit, the troy ounce, is used for precious metals.
The Conversion Formula
ounces = grams ÷ 28.3495For quick estimates: divide by 28. One ounce is approximately 28 grams.
Food Weight Reference
- 28 g = 1 oz (one serving of most snacks)
- 100 g = 3.527 oz
- 113 g = 4 oz (quarter-pound burger)
- 227 g = 8 oz (half-pound steak)
- 454 g = 16 oz = 1 lb
- 500 g = 17.64 oz
Avoirdupois vs Troy Ounce
The avoirdupois ounce (28.35 g) is used for food and everyday items. The troy ounce (31.10 g) is used exclusively for precious metals like gold and silver. A "1 oz gold coin" weighs 31.1 g, not 28.3 g. Never confuse these when dealing with jewellery or bullion.
Convert any weight instantly: Free grams to ounces converter
Complete Reference Table
- 25 g = 0.882 oz
- 50 g = 1.764 oz
- 100 g = 3.527 oz
- 150 g = 5.291 oz
- 200 g = 7.055 oz
- 250 g = 8.818 oz
- 500 g = 17.637 oz
- 1000 g (1 kg) = 35.274 oz
Avoirdupois vs Troy Ounces
The ounce used in everyday cooking and commerce is the avoirdupois ounce (28.3495 g). Precious metals — gold, silver, platinum — are measured in troy ounces (31.1035 g), which are about 10% heavier. If you are converting the weight of jewellery or investment metals, you must use the troy ounce conversion factor, not the standard one. Confusing the two on a 10-gram gold purchase would cause a pricing error of nearly 10%.
Real-World Applications
- Cooking: US recipes call for ingredients in ounces while European recipes use grams. A common conversion: 100 g butter ≈ 3.5 oz.
- Postal and shipping: Letter weights are assessed in grams in most countries but in ounces in the US. A 100 g letter = 3.5 oz.
- Nutrition labels: Serving sizes appear in grams globally; some older US labels use ounces.
- Sports nutrition: Protein supplement serving sizes are often given in grams, but some US brands use ounces.
Frequently Asked Questions
How many grams in an ounce exactly?
One avoirdupois ounce is exactly 28.349523125 grams, commonly rounded to 28.35 g. One troy ounce is exactly 31.1034768 grams. The international definitions are exact by convention.
Is a fluid ounce the same as a weight ounce?
No. A fluid ounce (fl oz) is a unit of volume, not weight. One US fluid ounce is approximately 29.57 mL. The confusion arises because one fluid ounce of water weighs approximately one weight ounce (28.35 g), but this only holds for water — other liquids differ.
What is the easiest mental shortcut?
A rough but useful rule: 100 grams ≈ 3.5 ounces. For kitchen purposes, this is close enough — 100 g flour ≈ 3.5 oz. For more precision, multiply grams by 0.0353 to get ounces.