Ounces to Grams: Conversion Formula and Calculator

Convert ounces to grams by entering a weight in ounces; the calculator multiplies it by the standard conversion factor and returns grams. Use it for ordinary weight measurements, such as ingredients or small parcels, and check whether your source means a standard ounce or a troy ounce before converting.

Formula

Grams = ounces × 28.349523125

• Ounces (oz) is the weight you enter, measured in avoirdupois ounces, the ordinary ounce used for most everyday goods.
• Grams (g) is the equivalent mass in the metric system.
• 28.349523125 grams per ounce is the exact conversion factor for an avoirdupois ounce.

For a quick estimate, multiply ounces by 28.35. Use the full factor when you need a more precise calculation, then round the final answer to a sensible number of decimal places for your task.

Worked Example

The calculator’s default input is 1 ounce. Substitute that value into the formula:

1. Start with 1 oz.
2. Multiply by the conversion factor: 1 × 28.349523125 = 28.349523125 g.
3. Round to the calculator’s two decimal places: 28.35 g.

So, 1 ordinary ounce is 28.35 grams when rounded to two decimal places.

What You’ll Need

• The weight in ounces. If you are measuring an object or ingredient yourself, use a scale set to ounces and place the item on it as directed by the scale.
• A calculator or the conversion calculator above. For a rough estimate, mental arithmetic is enough: one ounce is a little over 28 grams.
• The type of ounce, if the measurement comes from a specialized context. This calculator uses the ordinary avoirdupois ounce, not the troy ounce used for some precious metals.

Step-by-Step

1. Find the ounce value. Read the weight from the label, recipe, scale, or other source. Keep the number as written, including any decimal places or fraction.
2. Confirm which ounce is meant. Most everyday food, household, and shipping weights use avoirdupois ounces. Precious-metal measurements may use troy ounces, which are heavier. Do not convert a troy-ounce value with the everyday factor.
3. Enter the number of ounces. Type the value into the calculator’s Ounces field. Enter the number only; the field already specifies ounces. You can enter a decimal such as 2.5.
4. Multiply by 28.349523125. If calculating by hand, multiply the ounce amount by this factor. For example, 4 oz × 28.349523125 = 113.3980925 g.
5. Read the result in grams. The calculator displays grams rounded to two decimal places. In the example, 4 oz is 113.40 g to the nearest hundredth of a gram.
6. Choose rounding that suits the measurement. Keep extra digits during the calculation and round only the final answer. A kitchen recipe may not need hundredths of a gram, while a precision measurement may need a more suitable scale and a carefully stated precision.
7. Label the result clearly. Write “g” or “grams” beside the converted value. A bare number can be mistaken for ounces or another unit later.

Common Mistakes

• Using the wrong ounce. The everyday avoirdupois ounce is 28.349523125 g. A troy ounce is about 31.1035 g. Check the context, especially for metals or specialized trade measurements.
• Confusing ounces of weight with fluid ounces. A fluid ounce measures volume, not mass. You cannot convert fluid ounces to grams using this factor alone; the ingredient’s density is also needed. The gram result depends on what liquid or material is being measured.
• Dividing instead of multiplying. Since a gram is smaller than an ordinary ounce, the number in grams should be larger than the number in ounces. If your result is smaller, check the operation.
• Rounding too early. Multiplying by 28 or rounding each intermediate result can reduce accuracy. Use the full factor, then round once at the end.
• Mixing mass and weight terminology without checking the context. Everyday scales and recipes commonly call this “weight,” while grams formally express mass. For normal conversions, the stated ounce-to-gram factor is the one to use.
• Leaving off the unit. “113.40” alone is ambiguous. Include g, and preserve the original unit alongside it when recording a conversion.

Tips

• Use 28.35 for quick estimates. It is a rounded version of the exact factor and is usually convenient for everyday arithmetic.
• Use familiar reference points. One ounce is about 28.35 g, 2 oz is about 56.70 g, and 8 oz is about 226.80 g. These can help you spot an obviously incorrect answer.
• Convert the total, not each small part, when practical. If several amounts are being combined, add the ounce amounts first and convert the total. This can avoid small rounding differences between separately rounded values.
• Match precision to your tools. A result with many decimal places does not mean a kitchen scale can measure that precisely. Report no more precision than the source measurement and task justify.
• Keep the conversion direction straight. Ounces to grams: multiply by 28.349523125. Grams to ounces: divide by 28.349523125.

Troubleshooting

The answer seems far too large or too small: Check that you entered the number in ounces, rather than grams or fluid ounces. Confirm that you multiplied by about 28.35. For ordinary ounces, grams should be roughly 28 times the ounce amount.

The calculator rejects your entry: Enter a numeric value, such as 3, 0.5, or 2.75. If you have a mixed fraction such as 1½ ounces, convert it to a decimal first: 1.5 oz.

Your result does not match another converter: Compare the displayed precision and rounding rules. One calculator may show one decimal place and another may show two. Also check that both are converting avoirdupois ounces rather than troy ounces.

You have a volume measurement: Look for “fl oz” or “fluid ounces” on the source. To get grams, you need the density of the specific substance, or a reliable conversion for that ingredient. Do not treat a fluid ounce as an ounce of weight.

You need a particularly precise result: Keep the unrounded calculation, check the original measurement’s precision, and use a suitable calibrated scale if you are weighing the item. Extra calculator digits cannot correct an inaccurate starting measurement.

Frequently Asked Questions

How many grams are in 1 ounce?
One ordinary avoirdupois ounce is exactly 28.349523125 grams, or about 28.35 g.

What is the formula for ounces to grams?
Multiply the number of ounces by 28.349523125. The answer is in grams.

How do I convert grams back to ounces?
Divide the number of grams by 28.349523125. For example, 100 g ÷ 28.349523125 is about 3.53 oz.

Are fluid ounces the same as ounces?
No. A fluid ounce measures volume, while an ordinary ounce measures weight or mass. Converting a fluid-ounce amount to grams requires the measured substance’s density.

Is a troy ounce the same as an ordinary ounce?
No. A troy ounce is about 31.1035 g, compared with 28.3495 g for an ordinary avoirdupois ounce. Use the factor that matches the type of measurement.

How many decimal places should I use?
For routine conversions, two decimal places are often convenient. Follow the precision of the original measurement and the needs of the task; do not imply greater accuracy than the measurement supports.

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in oz | Ounces | oz | 1 | 0
out grams | Grams | g | oz * 28.349523125 | 2