How Many Grams in an Ounce – Grams to Ounces

How Many Grams in an Ounce
There are exactly 28.349523125 grams in an ounce.

If you wonder how many grams in an ounce or need to work grams to ounces conversions then you’ve come to the right place. The math is a simple matter of multiplication or division. Here is the unit conversion formula, with example calculations.

Grams to Ounces Formula

  • 1 ounce (oz) = 28.349523125 grams (g)
  • Rounded: 1 oz = 28.35 g or 1 oz = 28.3 g or 1 oz = 28 g
  • 1 gram (g) = 0.035274 ounces (oz)

Different Ounce Units

There is more than one type of “ounce,” so it’s important you’re dealing with the right one.

The ounce that is the unit of mass (like the gram) is the avoirdupois ounce. Since no one wants to write out “avoirdupois” all the time, it’s simply called an ounce (oz). The ounce is 1/16 of an avoirdupois pound (the Imperial pound, lb). So, there are 16 ounces in 1 pound. This type of ounce finds use measuring cooking ingredient sizes, medications, postal items, and paper.

There are also fluid ounces. The abbreviation for the fluid ounce is different (fl oz). The fluid ounce measures liquid and gas volumes. It is a unit of volume, not mass. The conversion factor to grams depends on the nature of the substance.

Ounce to gram conversions (and gram to ounce) conversions involve the avoirdupois ounce (oz).

How Many Grams in an Ounce?

There are 28.349523125 grams (g) in 1 ounce (oz). For scientific measurements, use the correct number of significant digits. Usually, this conversion factor is 28.35 grams in 1 ounce. For cooking and medicinal agents, the number gets rounded to either 28.3. For some measurements, it’s fine to use 28 grams to 1 ounce.

Grams to Ounces

Convert grams to ounce using a conversion formula:

1 ounce = 28.35 grams
ounces = grams ÷ 28.35

For example: How many ounces are in 100 grams?

ounces = grams ÷ 28.35
ounces = 100 ÷ 28.35 = 3.527 oz

Ounces to Grams

Again use the conversion formula:

1 ounce = 28.35 grams
grams = ounces x 28.35

For example, how many grams are in 16 ounces?

grams = ounces x 28.35
grams = 16 x 28.35 = 453.6 g

For example: How many grams are in 1/8th ounce?

In this example, note that ounces are not always given using decimal numbers. When this happens, first do the fraction to get get the decimal number and then do the unit conversion.

1/8 oz = 0.125 oz

Now, do the unit conversion:

grams = ounces x 28.35
grams = 0.125 x 28.35 = 3.54 g

Quick Grams to Ounces Conversion Table

If you don’t need precise measurements, use rounded values. Here is a table of grams to ounces conversions.

Common WeightsGrams (Rounded)
1/8 ounce3.5 grams
1/4 ounce7 grams
1/2 ounce14 grams
3/4 ounce21 grams
1 ounce28 grams
1 pound16 ounces or 454 grams
1 kilogram1000 grams


  • Barbrow, L.E.; Judson, L. V. (1976). Weights and Measures of the United States. National Bureau of Standards Special Publication 447.
  • Çengel, Yunus A.; Boles, Michael A. (2002). Thermodynamics: An Engineering Approach (8th ed.). McGraw Hill. ISBN 9780073398174.
  • National Institute of Standards and Technology. (2008). Guide for the Use of the International System of Units (SI).
  • Young, Hugh D; Freedman, Roger A. (2012). University Physics (13th ed.). Pearson Education Inc. ISBN 978-0-321-69686-1.

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