oz and fl oz: two different units
The word “ounce” is used for two completely unrelated measurement units. This is one of the most common sources of confusion in recipe conversion.
The numerical values are also different: 1 oz (mass) = 28.35 g, but 1 fl oz (volume) of water = 29.57 g. For a denser liquid like honey, 1 fl oz weighs approximately 39 g — because density determines how many grams fit in a given volume.
What is an avoirdupois ounce?
The avoirdupois ounce is a unit of mass defined as exactly 28.3495231 grams by the 1959 international yard and pound agreement. It is the standard ounce used in everyday measurement across the United States and in many other countries.
16 oz = 1 pound (lb) = 453.592 g • Used in US recipes, food packaging, postal weights, and product labels • Symbol: oz
Where the avoirdupois ounce is used
When a US recipe says “6 oz of chicken” or a food label lists “net weight 8 oz”, it always means the avoirdupois ounce. It is the default ounce in all food and cooking contexts.
Not the troy ounce
The troy ounce = 31.1035 g, is used exclusively for precious metals (gold, silver, platinum). It is never used in cooking or food measurement. If a recipe or food label says “oz”, it always means avoirdupois (28.35 g), not troy.
Not the fluid ounce
The fluid ounce (fl oz) is a unit of volume, not mass. 1 US fl oz = 29.5735 ml. The fluid ounce and the avoirdupois ounce are entirely different units that happen to share the word “ounce”. See the fluid ounces to ml page for volume conversions.
Ounces to Grams reference table
Complete conversion table from ¼ oz to 32 oz.
| Ounces | Grams | Pounds |
|---|---|---|
| ¼ oz | 7.1 g | |
| ½ oz | 14.2 g | |
| ¾ oz | 21.3 g | |
| 1 oz | 28.3 g | |
| 1.5 oz | 42.5 g | |
| 2 oz | 56.7 g | |
| 2.5 oz | 70.9 g | |
| 3 oz | 85 g | |
| 3.5 oz | 99.2 g | |
| 4 oz | 113.4 g | ¼ lb |
| 5 oz | 141.7 g | 0.3125 lb |
| 6 oz | 170.1 g | 0.375 lb |
| 7 oz | 198.4 g | 0.4375 lb |
| 8 oz | 226.8 g | ½ lb |
| 9 oz | 255.1 g | 0.5625 lb |
| 10 oz | 283.5 g | 0.625 lb |
| 12 oz | 340.2 g | ¾ lb |
| 14 oz | 396.9 g | 0.875 lb |
| 16 oz | 453.6 g | 1 lb |
| 20 oz | 567 g | 1.25 lb |
| 24 oz | 680.4 g | 1½ lb |
| 32 oz | 907.2 g | 2 lb |
Common food weights in ounces and grams
| Food | Typical oz | Grams |
|---|---|---|
| Butter stick (US) | 4 oz | 113 g |
| Cream cheese block | 8 oz | 227 g |
| Chicken breast (medium) | 6 oz | 170 g |
| Salmon fillet (medium) | 6 oz | 170 g |
| Dark chocolate bar | 3.5 oz | 99 g |
| Can of beans (drained) | 8 oz | 227 g |
| Block of cheese | 8 oz | 227 g |
| Ground beef patty | 4 oz | 113 g |
| Pasta (dry, 1 serving) | 2 oz | 57 g |
| Large egg | 2 oz | 57 g |
Pounds, ounces and grams
| Pounds | Oz | Grams |
|---|---|---|
| ¼ lb | 4 oz | 113 g |
| ½ lb | 8 oz | 227 g |
| ¾ lb | 12 oz | 340 g |
| 1 lb | 16 oz | 454 g |
| 1.5 lb | 24 oz | 680 g |
| 2 lb | 32 oz | 907 g |
Troy ounce vs avoirdupois ounce
1 troy oz = 31.1035 g. Used ONLY for precious metals. NEVER in cooking. If a recipe says “oz” it always means avoirdupois (28.35 g).
| Ounce type | Grams | Used for |
|---|---|---|
| Avoirdupois oz | 28.3495 g | Food, recipes, everyday weight |
| Troy oz | 31.1035 g | Gold, silver, platinum only |
The troy ounce is about 10% heavier than the avoirdupois ounce. Using the wrong value in a recipe would result in roughly 10% more ingredient than intended.
Frequently asked questions
How many grams is 1 ounce?
1 ounce (avoirdupois) equals exactly 28.3495 grams, commonly rounded to 28.35 g in everyday use. This is the standard ounce used in US recipes, food packaging, and postal weights.
How many grams is 4 ounces?
4 ounces equals 113.4 grams (4 × 28.3495 = 113.398 g). 4 oz is also equal to ¼ pound (0.25 lb). A standard US stick of butter weighs exactly 4 oz / 113 g.
How many grams is 8 ounces?
8 ounces equals 226.8 grams (8 × 28.3495 = 226.796 g). 8 oz is also equal to ½ pound (0.5 lb). Common foods sold in 8 oz packages include cream cheese blocks and blocks of cheese.
What is the difference between oz and fl oz?
oz (ounce) is a unit of mass: 1 oz = 28.3495 g. fl oz (fluid ounce) is a unit of volume: 1 US fl oz = 29.5735 ml. They share the word “ounce” in their names but measure completely different physical properties. You cannot directly convert between them without knowing the density of the substance.
Is a troy ounce the same as a regular ounce?
No. A troy ounce = 31.1035 g. A regular (avoirdupois) ounce = 28.3495 g. Troy ounces are used exclusively for precious metals such as gold, silver, and platinum. They are never used in cooking, food packaging, or everyday measurement. If a recipe says “oz”, it always means avoirdupois (28.35 g).
How many ounces is 100 grams?
100 grams = 3.527 oz (100 ÷ 28.3495 = 3.5274). For quick mental maths: 100 g ≈ 3½ oz.
How many ounces is 500 grams?
500 grams = 17.637 oz (500 ÷ 28.3495 = 17.637). This is approximately 1 pound 1.6 oz, or just over 1 lb.
How do I convert ounces to grams?
Multiply the number of ounces by 28.3495. Example: 6 oz × 28.3495 = 170.097 g ≈ 170 g. For a quick approximation, multiply by 28.35 or use the calculator at the top of this page.