How this calculator works
A gram is a mass and a US fluid ounce is a volume of 29.5735295625 mL, which is one hundred and twenty-eighth of a US gallon. Dividing grams by the density gives millilitres, and dividing millilitres by 29.5735295625 gives US fluid ounces. Water at room temperature is close to 1 g per mL, so 100 g of water is about 3.38140 US fl oz, while 100 g of honey at 1,420 kg/m3 is only about 2.38127 US fl oz. The page offers imperial fluid ounces and US spoon measures as well, and the preset densities are typical values.
Formula
millilitres = grams / density in g/mL. US fluid ounces = millilitres / 29.5735295625. grams = US fluid ounces x 29.5735295625 x density. Imperial fluid ounces use 28.4130625 mL.
Worked example
100 g of water is 3.38140 US fl oz. 100 g of milk at 1.030 g/mL is 3.28292 US fl oz. 100 g of honey at 1.420 g/mL is 2.38127 US fl oz. 8 US fl oz of water is 236.588 g, and 8 US fl oz of cooking oil at 0.920 g/mL is 217.66 g.
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Frequently asked questions
How many grams are in a fluid ounce?
It depends on the liquid. One US fluid ounce of water is about 29.57 g, milk about 30.46 g and honey about 42.00 g. The fluid ounce is a volume, so the mass follows the density.
Is a US fluid ounce the same as an imperial fluid ounce?
No. A US fluid ounce is 29.5735295625 mL and an imperial fluid ounce is 28.4130625 mL, so an imperial fluid ounce holds about 4 per cent less liquid and less mass.
Why does the answer differ from a kitchen cup measure?
A US customary cup is eight US fluid ounces, so one cup of water is about 236.588 g. Many Canadian recipes use a 250 mL metric cup, which is 250 g of water, so check which cup a recipe means.
Can I convert grams of flour to fluid ounces?
Only with a stated density. Milled flour packs down and its bulk density varies from about 500 to 600 kg/m3 depending on settling, so a volume measure of flour is unreliable. Weigh flour with a scale instead.