Grams to Ounces Converter & Formula

This calculator converts a weight in grams to ounces (avoirdupois). Enter the number of grams, and you get the equivalent weight in ounces, plus the same weight in pounds and ounces for convenience. The conversion uses the standard factor: 1 ounce = 28.349523125 grams.

Formula

The conversion from grams to ounces is a simple division:

ounces = grams ÷ 28.349523125

Where:

• grams – the mass you start with (unit: g)
• 28.349523125 – the exact number of grams in one avoirdupois ounce (unit: g/oz)
• ounces – the resulting mass (unit: oz)

For everyday cooking and food labels, most people round the divisor to 28.35 or even 28. The calculator above uses the exact value, so results match official definitions.

Worked Example

Using the default input of 100 grams:

1. Divide 100 by 28.349523125: 100 ÷ 28.349523125 = 3.527396195
2. Round to 2 decimal places: 3.53 ounces

So 100 grams equals 3.53 ounces. The second output shows the same weight as 0 lb 3.53 oz, because 100 grams is less than one pound (453.592 grams).

Why the Conversion Exists

Grams and ounces are both units of mass, but they come from different measurement systems. Grams are part of the metric system (SI), used almost everywhere in the world for science, medicine, and everyday trade. Ounces belong to the US customary and British imperial systems, still common in the United States for food, postal mail, and body weight.

Because both units measure the same physical quantity, converting between them is a matter of multiplying or dividing by a fixed constant. The constant is defined by international agreement, not by the size of an object or the force of gravity, so the conversion is exact and identical everywhere on Earth.

One common source of confusion is the fluid ounce, which measures volume, not mass. A fluid ounce of water weighs about 1.043 ounces, but a fluid ounce of oil weighs less. This calculator only handles mass ounces (avoirdupois), not fluid ounces.

How to Read the Result

The main result is the weight in ounces, rounded to two decimal places. That level of precision is fine for cooking, shipping, and most practical tasks. If you need more accuracy, increase the decimal places in the calculator (up to 6).

The second output shows the same weight expressed as pounds and ounces, which is how body weight and many grocery items are written in the US. For example, 500 grams becomes 1 lb 1.64 oz, not 17.64 oz. This format helps when you are comparing with a scale that shows pounds and ounces.

Be aware that rounding can cause small discrepancies. If you convert 100 g to 3.53 oz and then convert 3.53 oz back to grams, you get 100.07 g, not exactly 100 g. That is normal and rarely matters unless you are doing precision chemistry.

Common Mistakes and How to Avoid Them

• Using 28 instead of 28.35 – For 100 g, 100 ÷ 28 = 3.57 oz, which is 1% higher than the correct 3.53 oz. For large weights, the error grows.
• Confusing ounces with fluid ounces – A fluid ounce is a volume unit. You cannot convert grams to fluid ounces without knowing the density of the substance.
• Forgetting the difference between US and imperial ounces – For mass, they are the same (1 avoirdupois ounce = 28.349523125 g). The difference only appears in fluid ounces (US fl oz ≈ 29.57 mL, imperial fl oz ≈ 28.41 mL).
• Mixing up troy ounces – Precious metals use troy ounces (31.1035 g), not avoirdupois. This calculator uses the standard avoirdupois ounce for everyday weights.

When to Use This Converter

Use this converter whenever you have a weight in grams and need it in ounces. Typical situations include:

• Following a recipe written in US units when your scale shows grams
• Checking postal or shipping weights when the rate chart uses ounces
• Comparing product weights between metric and imperial labels
• Converting body weight from kilograms to pounds and ounces for personal records

For the reverse direction (ounces to grams), simply multiply the number of ounces by 28.349523125. For example, 8 oz × 28.35 = 226.8 g, which is a standard cup of flour by weight.

Limitations and Precision Notes

The conversion factor is exact by definition, so there is no inherent error in the math. The only limitations come from your input and your rounding:

• Input precision – If you enter 100 g, the result is exact to the decimal places shown. If you enter 100.5 g, the result reflects that.
• Rounding – The calculator rounds to 2 decimals by default. For baking, 0.1 oz is about 3 g, which can matter for very precise recipes. Increase decimals if needed.
• Scale accuracy – A kitchen scale that reads to 1 g has an uncertainty of ±0.5 g, which translates to about ±0.02 oz. That is usually negligible.

For scientific work, use the full factor (28.349523125) and carry extra digits through your calculation. The calculator does this internally, so the displayed result is as accurate as your input.

Frequently Asked Questions

How many grams are in an ounce?

Exactly 28.349523125 grams in one avoirdupois ounce. Most recipes and food labels use 28.35 g as a close approximation.

Is 100g equal to 4 ounces?

No, 100 g equals about 3.53 oz. The common “4 ounces� approximation comes from 113.4 g, which is exactly 4 oz. For quick mental math, 100 g is slightly more than 3.5 oz.

How do I convert grams to ounces without a calculator?

Divide the number of grams by 28.35. For example, 250 g ÷ 28.35 ≈ 8.82 oz. If you need a rough estimate, divide by 28 (which gives a slightly larger number) or multiply by 0.035 (which gives a good approximation).

What is the difference between a troy ounce and a regular ounce?

A troy ounce weighs 31.1035 g, used for gold, silver, and other precious metals. A regular (avoirdupois) ounce weighs 28.3495 g, used for food and everyday items. The two are not interchangeable.

Why do some recipes say “oz� but mean “fl oz�?

In US recipes, “oz� without a qualifier usually means weight (avoirdupois ounces), while “fl oz� means fluid ounces (volume). Dry ingredients like flour and sugar are measured by weight in grams or ounces; liquids are measured by volume in cups or fluid ounces. When in doubt, use a scale for dry ingredients.

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in g | Grams | g | 100 | 0
out oz | Ounces | oz | g / 28.349523125 | 2
out lb_oz | Pounds and ounces | - | floor(g / 453.59237) + " lb " + round((g - floor(g / 453.59237) * 453.59237) / 28.349523125, 2) + " oz" | 2