Convert g to oz Calculator: Grams to Ounces

This calculator converts a weight in grams (g) to ounces (oz) using the standard international avoirdupois ounce. Enter the number of grams, and you get the equivalent weight in ounces instantly, along with the exact conversion factor used. The result is rounded to two decimal places, which is precise enough for cooking, shipping, and everyday measurements.

Formula

The conversion uses the internationally agreed definition of the avoirdupois ounce:

1 ounce (oz) = 28.349523125 grams (g)

Therefore, to convert grams to ounces:

Ounces = Grams ÷ 28.349523125

Where:

• Grams (g) – the metric unit of mass you start with.
• Ounces (oz) – the imperial/US customary unit of mass you get back.
• 28.349523125 – the exact conversion factor, defined by international agreement in 1959.

For most practical purposes, you can use 28.35 as the divisor. The difference is less than 0.005% and only matters in scientific or pharmaceutical contexts.

Worked Example

Using the default value of 100 grams from the calculator above:

1. Start with the formula: Ounces = Grams ÷ 28.349523125
2. Plug in 100 g: 100 ÷ 28.349523125
3. Perform the division: 100 ÷ 28.349523125 = 3.527396195
4. Round to two decimal places: 3.53 oz

So 100 grams equals approximately 3.53 ounces. This matches the calculator’s output. A quick mental check: a standard chocolate bar is about 100 g, and a typical single serving of meat is 3–4 oz, so the result feels right.

Why the Conversion Factor Is 28.35 (Not 28 or 30)

Many people wonder why the ounce isn’t a round number of grams. The reason is historical: the ounce comes from the Roman uncia (one-twelfth of a Roman pound), which evolved into the British avoirdupois system. The metric system was designed later, in 1790s France, with no relation to the ounce. When countries agreed to standardize measurements in 1959, they defined the international pound as exactly 453.59237 grams. Since one pound equals 16 ounces, dividing 453.59237 by 16 gives 28.349523125 grams per ounce.

Some recipes and nutrition labels round this to 28.35 g or even 28 g for simplicity, but that introduces a 1.2% error. For precise baking or supplement dosing, always use the full factor.

Common Uses for Grams-to-Ounces Conversion

You’ll need this conversion in several everyday situations:

• Cooking and baking – Many European and Asian recipes list ingredients in grams, while US recipes use ounces. Converting lets you follow either.
• Nutrition and food labels – US labels show both grams and ounces; understanding the conversion helps you compare products.
• Shipping and postage – International packages are weighed in grams or kilograms, but some carriers quote rates per ounce.
• Jewelry and precious metals – Gold and silver are often quoted per troy ounce, but note that’s a different ounce (31.1035 g). This calculator uses the avoirdupois ounce for everyday items.
• Hobbies and crafts – Resin, clay, or yarn amounts may be given in one unit or the other.

Common Mistakes and How to Avoid Them

The most frequent error is mixing up the avoirdupois ounce (28.35 g) with the troy ounce (31.10 g) used for precious metals. If you’re weighing gold, use a troy-ounce calculator. Another common mistake is dividing when you should multiply. To go the other way (ounces to grams), you multiply by 28.35. Finally, watch out for rounding too early: if you round 28.3495 to 28 before dividing, you’ll get a result about 1.2% too high. For a 500 g package, that’s a 6 g error—enough to matter in shipping.

Also, be careful with fluid ounces. A fluid ounce measures volume, not weight. One fluid ounce of water weighs about 1.04 oz, but one fluid ounce of oil weighs less. This calculator is for mass (weight) only.

How to Do the Conversion Mentally

If you don’t have a calculator, here’s a quick approximation: divide the grams by 28.35, or roughly by 28. For a faster mental estimate, divide by 28 and then subtract 1% of the result. For example, 200 g ÷ 28 = 7.14 oz; subtract 0.07 to get about 7.07 oz. The exact answer is 7.05 oz, so this is close enough for most purposes.

Another trick: remember that 100 g ≈ 3.5 oz. So for 300 g, just multiply 3.5 × 3 = 10.5 oz (exact: 10.58 oz). For 50 g, it’s half of 3.5 = 1.75 oz (exact: 1.76 oz). These benchmarks help you sanity-check calculator results.

Limits of the Formula

The conversion is exact and universal—it doesn’t depend on temperature, pressure, or material. One gram of feathers and one gram of lead both convert to the same number of ounces. However, the precision of your result depends on the precision of your input. If you weigh something on a kitchen scale that reads to the nearest gram, your ounce result is only accurate to about ±0.035 oz. For scientific work, use a scale that reads to 0.01 g or better.

Also note that this calculator uses the international avoirdupois ounce, which is the standard in the US and UK for everyday goods. If you’re dealing with precious metals, pharmacy measurements (apothecary ounce), or historical documents, double-check which ounce is meant.

Frequently Asked Questions

How many grams are in an ounce?

Exactly 28.349523125 grams. Most people round to 28.35 g for everyday use. If a recipe says “1 oz� and you only have a gram scale, multiply by 28.35 to get the grams.

Is 30 g equal to 1 oz?

No, 30 g is slightly more than 1 oz. 1 oz is 28.35 g, so 30 g is about 1.06 oz. The difference is small but can matter in baking or when tracking food portions. Always use 28.35 for accuracy.

How do I convert grams to ounces in Excel or Google Sheets?

Use the formula =A1/28.349523125 where A1 contains the grams. Or use the built-in function =CONVERT(A1,"g","oz") in Excel (English version) or =CONVERT(A1,"g","oz") in Google Sheets. Both give the same result as this calculator.

What’s the difference between an ounce and a fluid ounce?

An ounce (oz) measures mass or weight. A fluid ounce (fl oz) measures volume. They are not interchangeable. For water, 1 fl oz weighs about 1.04 oz, but for oil, 1 fl oz weighs about 0.96 oz. Always check which one a recipe or label uses.

Why do some nutrition labels show “ozâ€� but the number doesn’t match my scale?

Nutrition labels often round to the nearest gram or half-ounce for simplicity. For example, a label might say “Net wt. 4 oz (113 g)� – the actual conversion of 4 oz is 113.4 g, but they round down. This is legal and common. For precise cooking, use the gram value.

Can I use this calculator for gold and silver?

No, this calculator uses the avoirdupois ounce (28.35 g). Precious metals are weighed in troy ounces (31.10 g). If you’re buying or selling gold, silver, or platinum, use a troy-ounce converter to avoid a 9% error.

Related

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in g | Grams | g | 100 | 0
out oz | Ounces | oz | g / 28.349523125 | 2