Ounces to Grams Converter

Conversion Table

How to Convert Ounces to Grams

Converting ounces to grams is a common weight conversion. Our free online calculator gives you an instant, precise result.

The Ounces to Grams Formula

The formula is: grams = oz × 28.3495. For example, 4 ounces → 4 × 28.3495 = 113.4 = 113.4 grams.

The key factor: 1 oz = 28.3495 g.

Common Uses

This conversion is commonly used for cooking recipes, postal weights, and nutrition labels. Whether you need a quick answer or a reference table, our converter has you covered.

Understanding Ounces to Grams Conversion

The formula is: grams = oz × 28.3495. For quick estimates, multiplying by 28 works well for everyday use.

This conversion is most commonly needed in cooking and baking. When a US recipe calls for 4 ounces of chocolate, that's about 113 grams. European bakers who want to follow American recipes need this conversion constantly.

Useful benchmarks: 1 oz = 28.35g, 4 oz = 113.4g (a standard stick of butter is 4 oz), 8 oz = 226.8g, 12 oz = 340.2g, 16 oz = 453.6g (1 pound).

Quick mental shortcut: multiply ounces by 30 for a rough estimate. This overshoots by about 6%, which is acceptable for most cooking applications.

Common Mistakes When Converting Ounces to Grams

• Using 30 instead of 28.35: Rounding to 30g per ounce is common but introduces a 5.8% error. For small quantities it's fine, but for a 16 oz bag of flour, the error is 26g (a significant baking difference).
• Confusing weight ounces and fluid ounces: "8 oz of butter" means 8 weight ounces (227g), while "8 oz of milk" usually means 8 fluid ounces (about 240 mL, which happens to weigh about 245g).
• Not converting recipe quantities correctly: A recipe calling for "one 14-ounce can" means the can's labeled net weight — which is already in weight ounces (397g).
• Forgetting that density matters for volume-to-weight: A "cup" of ingredient in ounces varies by density. A cup of sugar ≈ 7 oz (200g), a cup of flour ≈ 4.25 oz (120g), a cup of honey ≈ 12 oz (340g).

A Brief History of Weight Measurement

Weight measurement dates back to ancient Mesopotamia around 3000 BCE, where the first balance scales were used for trade. The Egyptians developed standard stone weights, and the Romans created a sophisticated system based on the "libra" — which is why we still use "lb" as the abbreviation for pounds.

The modern avoirdupois pound (16 ounces) became the standard in England during the 14th century, replacing the earlier troy pound (12 ounces, still used for precious metals). The word "avoirdupois" comes from Anglo-French meaning "goods of weight."

The kilogram was introduced during the French Revolution as part of the metric system. It was originally defined as the mass of one liter of water at 4°C (its maximum density). In 1889, a platinum-iridium cylinder called the International Prototype of the Kilogram (IPK) became the standard.

In 2019, the kilogram was redefined in terms of the Planck constant, making it the last SI base unit to be defined by a fundamental physical constant rather than a physical artifact. Today, most of the world uses kilograms, while the US, UK (for body weight), and a few other countries commonly use pounds.

Who Uses Weight Conversion?

Fitness Enthusiasts

Gym equipment may be labeled in either kilograms or pounds depending on the manufacturer and country. Converting between the two is essential for tracking progress and following workout programs.

Shipping and Logistics

International shipping requires weight in kilograms for customs declarations, while domestic US shipping often uses pounds. Accurate conversion is critical for calculating shipping costs and staying within weight limits.

Home Cooks and Bakers

Many international recipes specify ingredients in grams, while US recipes use ounces and cups. Precise weight conversion is especially important in baking, where ratios matter greatly.

Healthcare Professionals

Medication dosages are calculated based on body weight in kilograms. Converting a patient's weight from pounds to kilograms is a routine but critical calculation in medical settings.

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