Whether you’re following a recipe, buying jewelry, weighing precious metals, or converting measurements, you may ask: How many grams are in an ounce?
The answer depends on which type of ounce you’re using.
There are two common weight measurements:
- Avoirdupois ounce (used for everyday items)
- Troy ounce (used for gold, silver, platinum, and other precious metals)
Because these two ounces are different, understanding which one applies is important for accurate conversions.
In this guide, you’ll learn how many grams are in each type of ounce, when they are used, conversion formulas, practical examples, and frequently asked questions.
Quick Answer
| Ounce Type | Grams |
|---|---|
| Avoirdupois ounce | 28.3495 grams |
| Troy ounce | 31.1035 grams |
The avoirdupois ounce is used in everyday life, while the troy ounce is used in the precious metals industry.
What Is an Avoirdupois Ounce?
The avoirdupois ounce is the standard ounce used in the United States and many other countries for everyday weight measurements.
It is commonly used for:
- Food
- Meat
- Produce
- Baking ingredients
- Packages
- Household items
One avoirdupois ounce equals:
28.3495 grams
For everyday calculations, this is usually rounded to:
28.35 grams
What Is a Troy Ounce?
The troy ounce is a specialized unit used for measuring:
- Gold
- Silver
- Platinum
- Palladium
- Other precious metals
One troy ounce equals:
31.1035 grams
Unlike the everyday ounce, the troy ounce is heavier.
Why Are They Different?
The two systems developed independently.
Avoirdupois System
Designed for general trade and everyday goods.
Troy System
Developed centuries ago for weighing precious metals and gemstones.
Although both are called ounces, they are not interchangeable.
Avoirdupois Ounce to Gram Formula
To convert everyday ounces into grams:
Grams = Ounces × 28.3495
Examples:
- 1 oz = 28.35 g
- 2 oz = 56.70 g
- 4 oz = 113.40 g
- 8 oz = 226.80 g
- 16 oz = 453.59 g
Troy Ounce to Gram Formula
To convert troy ounces into grams:
Grams = Troy Ounces × 31.1035
Examples:
- 1 troy oz = 31.10 g
- 2 troy oz = 62.21 g
- 5 troy oz = 155.52 g
- 10 troy oz = 311.03 g
Gram to Ounce Formula
Avoirdupois
Ounces = Grams ÷ 28.3495
Troy
Troy Ounces = Grams ÷ 31.1035
Avoirdupois Conversion Chart
| Ounces | Grams |
| 1 | 28.35 |
| 2 | 56.70 |
| 3 | 85.05 |
| 4 | 113.40 |
| 5 | 141.75 |
| 8 | 226.80 |
| 10 | 283.50 |
| 16 | 453.59 |
Troy Ounce Conversion Chart
| Troy Ounces | Grams |
| 1 | 31.10 |
| 2 | 62.21 |
| 3 | 93.31 |
| 5 | 155.52 |
| 10 | 311.03 |
| 20 | 622.07 |
Avoirdupois vs. Troy Ounce
| Feature | Avoirdupois | Troy |
| Weight | 28.35 g | 31.10 g |
| Used For | Everyday items | Precious metals |
| Pounds | 16 oz per pound | 12 oz per troy pound |
| Common Uses | Food, groceries | Gold, silver |
The troy ounce is about 9.7% heavier than the avoirdupois ounce.
Common Uses
Avoirdupois Ounce
You’ll see it used for:
- Grocery products
- Meat
- Produce
- Coffee
- Flour
- Sugar
- Shipping
Troy Ounce
Used for:
- Gold coins
- Silver bars
- Platinum
- Bullion
- Investment metals
Whenever you see gold prices quoted, they are almost always quoted per troy ounce.
Metric Comparisons
| Unit | Equivalent |
| 1 avoirdupois ounce | 28.35 g |
| 1 troy ounce | 31.10 g |
| 1 pound | 453.59 g |
| 1 kilogram | 35.27 avoirdupois oz |
| 1 kilogram | 32.15 troy oz |
Practical Examples
Cooking
A recipe calling for:
- 8 ounces of cheese
means:
226.8 grams
Gold
A one-ounce gold coin usually weighs:
31.10 grams
because it uses the troy ounce.
Grocery Shopping
An 8-ounce steak weighs:
226.8 grams
using the avoirdupois system.
Tips for Accurate Weighing
- Use a digital kitchen scale for food.
- Use a jewelry scale for precious metals.
- Confirm whether “oz” means avoirdupois or troy.
- Never assume gold uses regular ounces.
- Read labels carefully before converting.
FAQs
How many grams are in one ounce?
A standard (avoirdupois) ounce equals:
28.3495 grams
How many grams are in one troy ounce?
One troy ounce equals:
31.1035 grams
Is a troy ounce heavier?
Yes.
A troy ounce is approximately 9.7% heavier than an avoirdupois ounce.
Why do gold and silver use troy ounces?
The precious metals industry has used the troy system for centuries because it provides a consistent international standard.
How many grams are in 16 ounces?
Sixteen avoirdupois ounces equal:
453.59 grams
Are ounces and troy ounces interchangeable?
No.
They represent different weight systems.
Which ounce is used for food?
Food is almost always measured using the avoirdupois ounce.
Common Mistakes to Avoid
- Confusing troy ounces with regular ounces.
- Using food conversions for gold.
- Assuming every ounce equals 28.35 grams.
- Ignoring which measurement system is being used.
Checking the type of ounce ensures accurate conversions.
Quick Facts
- 1 avoirdupois ounce = 28.35 grams
- 1 troy ounce = 31.10 grams
- Food uses avoirdupois ounces.
- Precious metals use troy ounces.
- A troy ounce is heavier than a regular ounce.
- Gold prices are quoted per troy ounce.
Final Thoughts
The answer to “How many grams are in an ounce?” depends on the type of ounce:
- Avoirdupois ounce = 28.3495 grams
- Troy ounce = 31.1035 grams
For everyday cooking, groceries, and household items, use the avoirdupois conversion. If you’re buying or selling gold, silver, or other precious metals, always use the troy ounce. Knowing the difference helps you make accurate conversions and avoid costly mistakes.
