How Many Grams in an Ounce? Complete Avoirdupois & Troy Ounce Conversion Guide

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.