How much is an ounce

Although Australia follows the metric system, many people still encounter the term ounce (oz) in everyday life, whether in cooking, precious metals, pharmaceuticals, or international trade. But how much is an ounce exactly?

The answer depends on the type of ounce being used, as there are two main variations:

  • Avoirdupois ounce (used for general weight measurements)
  • Troy ounce (used for measuring gold, silver, and other precious metals)

This article will break down the different types of ounces, their conversions to grams, and how they apply in various industries in Australia.

How much is an ounce in grams?

One ounce is 28.3495 grams. The ounce is an imperial unit of weight that is still used in the United States, the United Kingdom, and some industries in Australia.

Avoirdupois ounce (common ounce)

The avoirdupois ounce is the most commonly used ounce in everyday weight measurements.

✅ 1 avoirdupois ounce = 28.349523125 grams

For simplicity, it is often rounded to 28.35 grams.

Common uses of the avoirdupois ounce:

  • Cooking and baking – Some older Australian recipes or those from the US and UK may list ingredients in ounces.
  • Consumer products – Certain international food packaging may display weight in ounces.
  • Postal services – Some international shipping services reference ounces.

Troy ounce (used for precious metals)

The troy ounce is used primarily for gold, silver, platinum, and other precious metals.

✅ 1 troy ounce = 31.1034768 grams

This is slightly heavier than an avoirdupois ounce. If you’re buying or selling gold in Australia, you’ll see prices listed per troy ounce.

Common uses of the troy ounce:

  • Gold and silver trading – Australia has a thriving precious metals market, with troy ounces used in bullion pricing.
  • Jewellery industry – Gold and silver jewellery weights are often measured in troy ounces.
  • Coin collecting – Some collectible coins (such as the Australian Gold Kangaroo and the Perth Mint’s bullion coins) are measured in troy ounces.

Ounces and the metric system in Australia

Australia officially switched to the metric system in 1974, meaning grams and kilograms are now the standard units for weight. However, the ounce is still relevant in certain contexts.

📌 Why do ounces still matter in Australia?

  • Many international recipes use ounces, especially from the US and UK.
  • Gold and silver traders rely on troy ounces for pricing and transactions.
  • Older Australians may still refer to ounces for body weight (e.g., baby weight in ounces).

Converting ounces to grams in Australia

For Australians who need to convert ounces into grams, here’s a quick reference guide:

Avoirdupois ounce to grams

Ounces (oz)Grams (g)
1 oz28.35 g
2 oz56.70 g
5 oz141.75 g
10 oz283.50 g

Example:

If a recipe calls for 3 ounces of flour, you would convert it by multiplying: 3 oz × 28.35 g = 85.05 g

Troy ounce to grams (for precious metals)

Troy Ounces (t oz)Grams (g)
1 t oz31.10 g
2 t oz62.20 g
5 t oz155.52 g
10 t oz311.03 g

Example:

If gold is priced at $2,500 per troy ounce, then: 5 t oz of gold = 5 × 31.10 g = 155.52 g of gold.

Where ounces are commonly used in Australia

Despite the metric system, ounces are still referenced in many industries.

Cooking and baking

  • Recipes from the US and UK often use ounces instead of grams.
  • Measuring cups and spoons sometimes list ounces alongside millilitres and grams.
  • Australian food products imported from the US may display weight in ounces.

Example:

If an American recipe calls for 4 ounces of sugar, you would convert it to grams:

4 oz × 28.35 g = 113.40 g

Gold, silver, and precious metals

  • Gold bullion and coins in Australia are priced in troy ounces.
  • The Perth Mint issues gold and silver coins measured in troy ounces.
  • Jewellers and investors track gold prices in troy ounces.

Example:

If the gold price is $3,000 per troy ounce, then:

2 t oz of gold would cost 2 × $3,000 = $6,000

Pharmacies and medicine

  • Older pharmaceutical measurements sometimes use ounces, though most medicines in Australia are now measured in millilitres (mL) or grams (g).

Example:

If an old prescription calls for 2 ounces of liquid medicine, you would convert it to millilitres:

2 oz × 29.5735 mL = 59.15 mL

Why understanding ounces matters in Australia

Even though Australia follows the metric system, knowing how to convert ounces to grams is essential for:

  • Cooking and baking
  • Buying and selling gold and silver
  • Understanding international products and measurements
  • Following medical dosages in old prescriptions

Whether you’re a home cook, investor, or simply curious about weight conversions, having a grasp of how much an ounce is in grams ensures you stay informed and precise.

Final thoughts

So, how much is an ounce?

  • 1 avoirdupois ounce = 28.35 grams (used in everyday weight measurements)
  • 1 troy ounce = 31.10 grams (used in precious metals)

For Australians, ounces remain relevant in cooking, gold trading, and international commerce, even though grams and kilograms are the standard units of measurement.

Next time you see a measurement in ounces, you’ll know exactly how to convert it into grams!